Updated on 2024/05/20

写真a

 
SHIBATA, Takanori
 
Affiliation
Faculty of Science and Engineering, School of Advanced Science and Engineering
Job title
Professor
Degree
(BLANK) ( The University of Tokyo )
博士(理学) ( 東京大学 )

Education Background

  •  
    -
    1994

    University of Tokyo   Graduate School, Division of Science   Organic Chemistry  

  •  
    -
    1989

    University of Tokyo   Faculty of Science  

Professional Memberships

  •  
     
     

    Synthetic Organic Chemistry, Japan

  •  
     
     

    Chemical Society of Japan

  •  
     
     

    American Chemical Society

  •  
     
     

    The Kinki Chemical Society, Japan

Research Areas

  • Bioorganic chemistry / Structural organic chemistry and physical organic chemistry / Synthetic organic chemistry

Research Interests

  • 有機金属触媒、不斉合成、合成有機化学、有機元素化学

Awards

  • Nissan Chemical Industries Award for Novel Reaction & Method

    2018.02   The Society of Synthetic Organic Chemistry   Efficient Synthetic Transformations Using Iridium and Rhodium Catalysts

    Winner: SHIBATA, Takanori

  • Incentive Award in Synthetic Organic Chemistry

    2005.02   The Society of Synthetic Organic Chemistry  

  • Daicel Award in Synthetic Organic Chemistry

    1997.02   The Society of Synthetic Organic Chemistry  

 

Papers

  • Experimental and Theoretical Evidence for Relativistic Catalytic Activity in C–H Activation of N-Phenylbenzamide Using a Cationic Iridium Complex

    Chinami Takashima, Hisaki Kurita, Hideaki Takano, Yasuhiro Ikabata, Takanori Shibata, Hiromi Nakai

    The Journal of Physical Chemistry A    2022.10

    DOI

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  • Enantioselective Cross-Coupling of Electron-Deficient Alkenes via Ir-Catalyzed Vinylic sp2 C-H Alkylation.

    Takanori Shibata, Masafumi Kojima, Sahoko Onoda, Mamoru Ito

    Organic letters    2021.10  [International journal]

     View Summary

    A chiral Ir-catalyzed reaction of α-aryl-α,β-unsaturated amides with β-substituted acrylates proceeded to give formal conjugate adducts in high yield and ee (up to 99% yield and up to 95% ee). This is the first example of the enantioselective cross-coupling of two different electron-deficient alkenes via vinylic sp2 C-H activation, and polyfunctionalized chiral compounds were obtained.

    DOI PubMed

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  • Ni-catalyzed non-activated C-S bond cleavage at ambient temperature for the synthesis of sulfur-containing polycyclic compounds.

    Takanori Shibata, Ayato Sekine, Mika Akino, Mamoru Ito

    Chemical communications (Cambridge, England)   57 ( 72 ) 9048 - 9051  2021.09  [International journal]

     View Summary

    A Ni-catalyzed intramolecular reaction of diarylthioether-tethered 1,8-diynes gave sulfur-containing tetracyclic compounds at ambient temperature. The transformation was initiated by non-activated sp2 C-S bond cleavage along with consecutive alkyne insertions. A double intramolecular reaction of a tetrayne and an intermolecular reaction of monoynes were also available, and the corresponding polycyclic compounds were obtained. Moreover, the obtained cycloadduct showed photo-catalytic activity in benzylic oxidation.

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  • Versatile Transformations of Biphenylenes by Transition-Metal Catalysts and Application for the Synthesis of Polycyclic Hydrocarbons

    Hideaki Takano, Takanori Shibata

    Journal of Synthetic Organic Chemistry, Japan   79 ( 9 ) 849 - 858  2021.09  [Refereed]

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  • Synthesis and Chiroptical Properties of Quinoxaline-Fused Polyaza[5]-[7]helicenes with Orange-Color CPL Emissions

    Takashi Otani, Takuma Sasayama, Masashi Horiuchi, Shunnosuke Okauchi, Hidetoshi Kawai, Maho Kitahara, Yoshitane Imai, Takanori Shibata

    HELVETICA CHIMICA ACTA   104 ( 4 )  2021.03

     View Summary

    We achieved a two-type synthesis of quinoxaline-fused polyaza[5]- and [7]helicenes through consecutive N-H/C-H coupling with a hypervalent iodine reagent as a key reaction. By fusing electron-deficient quinoxaline, these polyazahelicenes constitute an efficient donor-acceptor type of molecule with absorption edges that reach up to approximately 650 nm. Evaluating the chiroptical properties reveals that the polyazahelicene exhibits a rare orange circularly polarized glow with a luminescence dissymmetry factor (g(lum) value) of 0.003.

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  • Pt(II)-Chiral Diene-Catalyzed Enantioselective Formal [4+2] Cycloaddition Initiated by C-C Bond Cleavage and Elucidation of a Pt(II)/(IV) Cycle by DFT Calculations

    Takanori Shibata, Natsumi Shiozawa, Shun Nishibe, Hideaki Takano, Satoshi Maeda

    Organic Chemistry Frontiers    2021

     View Summary

    A chiral Pt(II) complex was readily prepared from [PtCl2(C2H4)]2 and Hayashi’s diene. Its dicationic derivative efficiently catalyzed a formal intramolecular [4+2] cycloaddition of biphenylenes possessing substituted arylalkynes tethered by an...

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  • Gold-catalyzed dual C-C bond cleavage of biphenylenes bearing a pendant alkyne at ambient temperature.

    Hideaki Takano, Sari Okazaki, Shun Nishibe, Takeharu Ito, Natsumi Shiozawa, Natsuhiko Sugimura, Kyalo Stephen Kanyiva, Takanori Shibata

    Organic & biomolecular chemistry   18 ( 30 ) 5826 - 5831  2020.08  [International journal]

     View Summary

    We report a catalytic skeletal rearrangement of biphenylenes with a pendant alkyne moiety at room temperature by a cationic gold catalyst, which involves the cleavage of two bonds: the C-C bond of biphenylene and the C(sp)-C(sp2 or sp3) bond. Experimental and theoretical studies revealed that the reaction mechanism included π-activation of the alkyne, ring expansion and 1,2-carbon shift.

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  • Catalytic Enantioselective Synthesis of Axially Chiral Polycyclic Aromatic Hydrocarbons (PAHs) via Regioselective C-C Bond Activation of Biphenylenes.

    Hideaki Takano, Natsumi Shiozawa, Yoshitane Imai, Kyalo Stephen Kanyiva, Takanori Shibata

    Journal of the American Chemical Society   142 ( 10 ) 4714 - 4722  2020.03  [International journal]

     View Summary

    Chiral polycyclic aromatic hydrocarbons (PAHs) are expected to have unusual physical properties due to their chirality and expanded π-conjugated system. Indeed, PAHs are promising compounds as chiral recognizers and organic semiconductors. Therefore, an efficient method for the synthesis of chiral PAHs is strongly desired. In contrast to helically chiral PAHs, there are only limited examples of the enantioselective synthesis of axially chiral PAHs. Herein, we report the catalytic enantioselective synthesis of benzo[b]fluoranthene-based axially chiral PAHs in excellent yields and enantioselectivities (up to >99%, >99% ee) by regioselective cleavage of the sterically hindered C-C bond of biphenylenes. The consecutive cyclizations could provide polycyclic PAHs with two chiral axes. The obtained chiral PAHs have high ε values (up to ε = 8.9 × 104), quantum yields (up to Φ = 0.67), and circularly polarized luminescence (CPL) property (|glum| = up to 3.5 × 10-3).

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  • Short-step synthesis and chiroptical properties of polyaza[5]–[9]helicenes with blue to green-colour emission

    Takashi Otani, Takuma Sasayama, Chisaki Iwashimizu, Kyalo Stephen Kanyiva, Hidetoshi Kawai, Takanori Shibata

    Chemical Communications   56 ( 32 ) 4484 - 4487  2020  [Refereed]  [International journal]

     View Summary

    <p>We have developed a two- or three-step synthesis of polyaza[5]–[9]helicenes by consecutive N–H/C–H coupling with a hypervalent iodine reagent.</p>

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  • Iodine-Catalyzed Synthesis of Chiral 4-Imidazolidinones Using α-Amino Acid Derivatives via Dehydrogenative N-H/C(sp3)-H Coupling.

    Kyalo Stephen Kanyiva, Marina Tane, Takanori Shibata

    The Journal of organic chemistry   84 ( 20 ) 12773 - 12783  2019.10  [International journal]

     View Summary

    An efficient method for the asymmetric synthesis of 4-imidazolidinones via an iodine-catalyzed intramolecular N-H/C(sp3)-H activation of readily available and abundant feedstocks, amino acids, and amines is described. The reaction proceeded under visible light irradiation to afford a variety of 4-imidazolidinone derivatives under mild conditions in moderate to excellent yields. Secondary and tertiary C(sp3)-H bonds were aminated, and various functional groups were tolerated.

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  • Relativistic Effect on Homogeneous Catalytic Reaction by Cationic Iridium Catalysts

    Chinami Takashima, Yasuhiro Ikabata, Hisaki Kurita, Hideaki Takano, Takanori Shibata, Hiromi Nakai

    Journal of Computer Chemistry, Japan   18 ( 3 ) 136 - 138  2019.10  [Refereed]

     View Summary

    A cationic Ir complex was reported to show specific catalytic activity in C-H bond activation reaction of benzanilides. The present study examined reaction energy profiles of the C-H bond activation with Ir and Rh catalysts based on non-relativistic and relativistic quantum chemical calculations. We found that the relativistic effect is essential to demonstrate the difference in the catalytic activity. In particular, the activation of the d orbital of Ir, which is caused by the s- and p- orbital contraction followed by the self-consistent d-orbital expansion, leads to stabilization of the transition state and product of the C-H bond activation.

    DOI

  • Consecutive HDDA and TDDA reactions of silicon-tethered tetraynes for the synthesis of dibenzosilole-fused polycyclic compounds and their unique reactivity.

    Akihito Mitake, Rikako Nagai, Ayato Sekine, Hideaki Takano, Natsuhiko Sugimura, Kyalo Stephen Kanyiva, Takanori Shibata

    Chemical science   10 ( 27 ) 6715 - 6720  2019.07  [International journal]

     View Summary

    Silicon-tethered tetraynes possessing a 1,3-diyne moiety underwent consecutive hexadehydro- and tetradehydro-Diels-Alder reactions to give a series of fused polycyclic aromatic compounds containing a dibenzosilole skeleton. The benzene ring in the product acted as a 1,3-diene and reacted with the active alkyne as well as oxygen to provide [4 + 2] cycloadducts.

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  • Intramolecular Consecutive Dehydro-Diels-Alder Reaction for the Catalytic and Enantioselective Construction of Axial Chirality.

    Takanori Shibata, Ayato Sekine, Akihito Mitake, Kyalo Stephen Kanyiva

    Angewandte Chemie (International ed. in English)   57 ( 48 ) 15862 - 15865  2018.11  [International journal]

     View Summary

    Consecutive thermal and metal-catalyzed dehydro-Diels-Alder (DDA) reactions of sulfur-tethered tetraynes, possessing a 1,3-diyne moiety, proceeded efficiently, and axial chirality was achieved for the resulting dibenzothiophenyl moieties. Chiral-rhodium catalysis realized a highly enantioselective synthesis, and transformations into bis(benzocarbazole) derivatives were also achieved.

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  • Regioselective Activation of a Sterically More Hindered C−C Bond of Biphenylenes Using an Alkene as Both a Directing Group and a Reaction Moiety

    Hideaki Takano, Takeharu Ito, Kyalo Stephen Kanyiva, Takanori Shibata

    Chemistry – A European Journal   24 ( 57 ) 15173 - 15177  2018.10

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  • Catalytic Dearomative Spirocyclization via Gold Carbene Species Derived from Ynamides: Efficient Synthesis of 2-Azaspiro[4.5]decan-3-ones

    Mamoru Ito, Ryosuke Kawasaki, Kyalo Stephen Kanyiva, Takanori Shibata

    Chemistry - A European Journal   24 ( 15 ) 3721 - 3724  2018.03  [Refereed]

     View Summary

    An intramolecular catalytic dearomatization of phenols via gold carbene species proceeded to provide 2-azaspiro[4.5]decan-3-ones. The use of NHC ligand and water as a co-solvent was critical for achieving high reactivity. This reaction did not require hazardous diazo compounds as carbene sources and proceeded even under air. The obtained spirocyclic product could be readily transformed into a gabapentin derivative by hydrogenation and deprotection.

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  • Ir-Catalyzed Synthesis of Substituted Tribenzosilepins by Dehydrogenative C-H/Si-H Coupling

    Takanori Shibata, Ninna Uno, Tomoya Sasaki, Hideaki Takano, Tatsuki Sato, Kyalo Stephen Kanyiva

    J. Org. Chem.    2018.03  [Refereed]

  • DFT Studies on the Mechanism of the Iridium-Catalyzed Formal [4 + 1] Cycloaddition of Biphenylene with Alkenes

    Hideaki Takano, Natsuhiko Sugimura, Kyalo Stephen Kanyiva, Takanori Shibata

    ACS Omega    2017.08  [Refereed]

  • Sulfur-directed carbon-sulfur bond cleavage for Rh-catalyzed regioselective alkynylthiolation of alkynes

    Takanori Shibata, Akihito Mitake, Yosuke Akiyama, Kyalo Stephen Kanyiva

    CHEMICAL COMMUNICATIONS   53 ( 64 ) 9016 - 9019  2017.08  [Refereed]

     View Summary

    Sulfur-directed sp C-S bond cleavage along with a regioselective reaction with alkynes proceeded to give (Z)-enyne sulfides in high to excellent yields. Mechanistic studies were conducted, including characterization of an intermediate. An intramolecular variant realized the construction of a dibenzodithiepin skeleton, which is a seven-membered ring with two sulfur atoms.

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  • Intramolecular C-H Alkenylation of N-Alkynylindoles: Exo and Endo Selective Cyclization According to the Choice of Metal Catalyst

    Takanori Shibata, Takumi Baba, Hideaki Takano, Kyalo Stephen Kanyiva

    ADVANCED SYNTHESIS & CATALYSIS   359 ( 11 ) 1849 - 1853  2017.06  [Refereed]

     View Summary

    The intramolecular reaction of 3-acetyl-N-alkynylindoles proceeded via C-H bond cleavage at the C2 position. Iridium and rhodium catalysts selectively promoted 6-exo-dig and 7-endo-dig cyclization, respectively, and N-fused tricyclic compounds were obtained.

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  • Cationic Au(I)-catalyzed cycloisomerization of N-(2-alkynylphenyl)indolines for the construction of indolobenzazepine skeleton

    Mamoru Ito, Daisuke Inoue, Ryosuke Kawasaki, Kyalo Stephen Kanyiva, Takanori Shibata

    Heterocycles   94 ( 12 ) 2229 - 2246  2017  [Refereed]

     View Summary

    An intramolecular reaction of N-(2-alkynylphenyl)indolines proceeded efficiently to give indolo[1,7-ab][1]benzazepine derivatives in high to excellent yields by cationic Au(I)-catalyzed 7-endo-dig selective cycloisomerization along with DDQ oxidation. The present transformation could be used for the intramolecular reaction of N-(2-alkynylphenyl)-1,2,3,4-tetrahydroquinoline and N-(2-alkynylphenyl)-N-methylaniline, and construction of a dibenzazepine skeleton was achieved.

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  • CATALYTIC INTRAMOLECULAR [2+2+2] CYCLOADDITION OF PEPTIDE-TETHERED BRANCHED TRIYNES FOR THE SYNTHESIS OF CYCLIC PEPTIDES

    Shuhei Obinata, Yu-ki Tahara, Kyalo Stephen Kanyiva, Takanori Shibata

    HETEROCYCLES   95 ( 2 ) 1121 - 1131  2017.01  [Refereed]

     View Summary

    Rhodium-catalyzed intramolecular [2+2+2] cycloaddition of peptide-tethered branched triynes gave cyclic peptides in moderate to excellent yields. This is a new catalytic protocol for the synthesis of cyclic peptides containing various amino acids.

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  • Iridium-catalyzed enantioselective Pauson-Khand-type reaction of 1,6-enynes

    T Shibata, N Toshida, M Yamasaki, S Maekawa, K Takagi

    TETRAHEDRON   61 ( 42 ) 9974 - 9979  2005.10

     View Summary

    Iridium-chiral diphosphine complex catalyzes an enantioselective intramolecular Pauson-Khand-type reaction to give various chiral bicyclic cyclopentenones. The enantioselective reaction proceeds more smoothly and enantioselectively under a lower partial pressure of carbon monoxide. Moreover, aldehyde can be used as a CO source in the enantioselective carbonylative coupling. (c) 2005 Elsevier Ltd. All rights reserved.

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  • Enantioselective construction of quaternary carbon centers by catalytic [2+2+2] cycloaddition of 1,6-enynes and alkynes

    T Shibata, Y Arai, Y Tahara

    ORGANIC LETTERS   7 ( 22 ) 4955 - 4957  2005.10

     View Summary

    [GRAPHICS]
    The enantioselective [2 + 2 + 2] cycloaddition of 1,6-enynes and alkynes using chiral rhodium catalysts gave cycloadducts containing quaternary carbon stereocenters. Both symmetrical and unsymmetrical alkynes and acetylene could be used as coupling partners, and the corresponding bicyclic cyclohexa-1,3-dienes were obtained in good to excellent ee.

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  • Iridium-catalyzed enantioselective cycloisomerization of nitrogen-bridged 1,6-enynes to 3-azabicylo[4.1.0]heptenes

    T Shibata, Y Kobayashi, S Maekawa, N Toshida, K Takagi

    TETRAHEDRON   61 ( 38 ) 9018 - 9024  2005.09

     View Summary

    A cationic iridium complex catalyzes a cycloisomerization of nitrogen-bridged 1,6-enynes to give 3-azabicyclo[4.1.0]heptenes in good to high yield. When an iridium-chiral diphosphine complex is used, the reaction proceeds enantiomerically to give chiral cyclopropanes fused by a six-membered ring system. (c) 2005 Elsevier Ltd. All rights reserved.

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  • Thermal and Au(I)-catalyzed intramolecular [4+2] cycloaddition of aryl-substituted 1,6-diynes for the synthesis of biaryl compounds

    T Shibata, R Fujiwara, D Takano

    SYNLETT   2005 ( 13 ) 2062 - 2066  2005.08

     View Summary

    1,6-Diynes, possessing aryl groups on their termini, undergo an intramolecular [4+2] cycloaddition via strained cyclic allene intermediates to give various biaryl compounds. Under thermal conditions, isomerization of the intermediates occurs, while, in the presence of a cationic gold catalyst, skeletal rearrangement is a major pathway.

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  • Cationic platinum-catalyzed etherification by intra- and intermolecular dehydration of alcohols

    T Shibata, R Fujiwara, Y Ueno

    SYNLETT   2005 ( 1 ) 152 - 154  2005.01

     View Summary

    Catalytic etherification of diols proceeds to give various cyclic ethers by use of cationic platinum salt, which is in situ prepared from PtCl2 and AgSbF6. Etherification of benzylic alcohols is also possible by intermolecular dehydration. Both of intra- and intermolecular etherifications smoothly proceed even under an atmosphere of air.

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  • Ir-catalyzed almost perfect enantioselective synthesis of helical polyaryls based on an axially-chiral sequence

    T Shibata, K Tsuchikama

    CHEMICAL COMMUNICATIONS   2005 ( 48 ) 6017 - 6019  2005

     View Summary

    Ir-catalyzed enantioselective [2 + 2 + 2] cycloaddition of tetraynes or an octayne with monoalkynes proceeded to give helically-chiral quinquearyl and noviaryl compounds, which respectively have four and eight consecutive axial chiralities, in an almost enantiomerically pure form.

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  • Iridium complex-catalyzed intramolecular ene-type reaction of 1,6-enynes accelerated in ionic liquid

    T Shibata, M Yamasaki, S Kadowaki, K Takagi

    SYNLETT   2004 ( 15 ) 2812 - 2814  2004.12

     View Summary

    Iridium complex catalyzes an intramolecular ene-type reaction of 1,6-enynes to give cyclic 1,4-dienes. The reaction proceeds more efficiently in an imidazolium salt than in toluene and the ionic liquid can be reused.

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  • The reaction of butatrienolates with aldehydes for the syntheses of alpha-vinylidene acylsilanes

    T Shibata, K Takami, Y Arai, K Tsuchikama, S Maekawa

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   77 ( 10 ) 1937 - 1938  2004.10

     View Summary

    Lithium butatrienolates were prepared in situ by the 1,4-elimination from 2-butynyl trimethylsilyl ethers along with a retro-Brook rearrangement. The addition reaction of the enolates with the aldehydes afforded beta-hydroxy-alpha-vinylidene acylsilanes.

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  • Chemo- and regioselective intramolecular hydrosilylative carbocyclization of allenynes

    T Shibata, S Kadowaki, K Takagi

    ORGANOMETALLICS   23 ( 17 ) 4116 - 4120  2004.08

     View Summary

    Rhodium complex catalyzed hydrosilylative carbocyclization of various allenynes and trialkoxysilanes proceeded smoothly under an atmosphere of carbon monoxide to give hydrosilylated cyclic products. The intramolecular coupling of allene and alkyne is chemo- and regioselective: silylrhodation to an internal olefinic moiety of the allene proceeded exclusively, and subsequent carbometalation to the alkyne provided cyclic 1,4-dienes. The use of alkoxysilane and the substituents on the allene terminus play pivotal roles in the selectivity.

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  • Iridium complex-catalyzed highly enantio- and diastereoselective [2+2+2] cycloaddition for the synthesis of axially chiral teraryl compounds

    T Shibata, T Fujimoto, K Yokota, K Takagi

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   126 ( 27 ) 8382 - 8383  2004.07

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  • Discovery and development of asymmetric autocatalysis

    K Soai, T Shibata, Sato, I

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   77 ( 6 ) 1063 - 1073  2004.06

     View Summary

    Asymmetric autocatalysis occurs when a chiral product operates as an asymmetric catalyst for its own production. We have discovered an asymmetric autocatalytic reaction in the enantioselective addition of dialkylzine to pyridine-3-carbaldehyde, where the product, 3-pyridyl alkanol, acts as an asymmetric autocatalyst. A diol, ferrocenyl alkanol, 5-pyrimidyl alkanol, and 3-quinolyl alkanol were also found to be asymmetric autocatalysts for the enantioselective isopropylation of the corresponding aldehydes. Of these compounds, 5-(2-alkynyl)pyrimidyl alkanol was the best asymmetric autocatalyst, and the asymmetric autocatalytic isopropylation of the corresponding pyrimidine-5-carbaldehyde proceeded quantitatively (&gt;99%), affording itself as a near enantiomerically pure (&gt;99.5% ee) chiral product. When an asymmetric autocatalyst with an extremely low ee was used, the asymmetric autocatalytic reaction proceeded along with amplification of the ee, and a highly enantiomerically enriched product was obtained. When the enantioselective isopropylation of pyrimidine-5-carbaldehydes was examined in the presence of chiral organic compounds with a very low ee acting as chiral initiators, then highly enantiomerically enriched 5-pyrimidyl alkanols were obtained. Their absolute configurations were dependent upon the slight excess of enantiomer in the chiral initiators. Chiral inorganic crystals, such as quartz and sodium chlorate, also act as chiral initiators. In conjunction with asymmetric autocatalysis, the chirality of organic compounds with a high enantiomeric excess has been correlated for the first time with the circularly polarized light and chiral inorganic crystals. Moreover, when an enantioselective isopropylation was examined in the absence of a chiral initiator, asymmetric induction above the detection level was observed in the product, with the ratio of the resulting predominant Sand R-isomers being almost equal. This result fulfills one of the conditions necessary for spontaneous absolute asymmetric synthesis.

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  • Iridium complex-catalyzed Pauson-Khand-type reaction of allenynes

    T Shibata, S Kadowaki, M Hirase, K Takagi

    SYNLETT   2003 ( 4 ) 573 - 575  2003.03

     View Summary

    Vaska's complex [IrCl(CO)(PPh3)(2)] efficiently catalyzes the intramolecular carbonylative [2+2+1] cycloaddition of allenynes. A dimethyl substituent on the allene terminus and a low partial pressure of carbon monoxide realize the selective engagement of the internal it-bond of allene.

  • Functionalized arylzinc compounds in ethereal solvent: Direct synthesis from aryl iodides and zinc powder and application to Pd-catalyzed reaction with allylic halides

    R Ikegami, A Koresawa, T Shibata, K Takagi

    JOURNAL OF ORGANIC CHEMISTRY   68 ( 6 ) 2195 - 2199  2003.03

     View Summary

    Arylzinc compounds, ArZnX, were conveniently prepared in high yields by the reaction of zinc powder with aryl iodides, which contain electron-withdrawing groups such as CO2CH3, CN, Br, or CF3 at the ortho-, meta- or para-position, or electron-donating groups such as CH3, OCH3, or H, at 70 degreesC in THF, at 100 degreesC, or at 130 degreesC in diglyme, respectively. Pd(dba)(2) exhibited an outstanding efficient catalytic effect for the cross-coupling of these ethereal solutions of ArZnX with allylic halides to afford a variety of functionalized allylbenzenes in high yields; the reactions were mostly carried out at 0 degreesC for 5-30 min in the presence of 5 mol % of catalyst. The conversion of the aryl iodides to allylbenzenes via two reactions could be accomplished in one pot.

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  • Rhodium complex-catalyzed intramolecular ene-type reaction of allenynes

    T Shibata, Y Takesue, S Kadowaki, K Takagi

    SYNLETT   2003 ( 2 ) 268 - 270  2003.02

     View Summary

    Wilkinson's catalyst [RhCl(PPh3)3] catalyzed a cyclo-isomerization of allenynes which possess geminal methyls on the allene terminus and an intramolecular ene-type reaction proceeded to give various cross-conjugated trienes. Thermal Diels-Alder reaction of the obtained triene was examined to give a bicyclic compound in a high yield.

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  • Asymmetric synthesis of pyrimidyl alkanol without adding chiral substances by the addition of diisopropylzinc to pyrimidine-5-carbaldehyde in conjunction with asymmetric autocatalysis

    K Soai, Sato, I, T Shibata, S Komiya, M Hayashi, Y Matsueda, H Imamura, T Hayase, H Morioka, H Tabira, J Yamamoto, Y Kowata

    TETRAHEDRON-ASYMMETRY   14 ( 2 ) 185 - 188  2003.01

     View Summary

    Enantiomerically enriched pyrimidyl alkanol with either S or R configuration was obtained stochastically from the reaction between pyrimidine-5-carbaldehyde and diisopropylzinc without adding chiral substances in conjunction with subsequent asymmetric autocatalysis, leading to amplification of the enantiomeric excess. (C) 2003 Elsevier Science Ltd. All rights reserved.

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  • Amplification of chirality from extremely low to greater than 99.5 % ee by asymmetric autocatalysis

    Sato, I, H Urabe, S Ishiguro, T Shibata, K Soai

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   42 ( 3 ) 315 - +  2003

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  • Palladium-catalyzed synthesis of 2,2-dimethyl-3-pyrrolines from alpha-aminoallene and aryl iodides

    T Shibata, S Kadowaki, K Takagi

    HETEROCYCLES   57 ( 12 ) 2261 - 2266  2002.12

     View Summary

    Palladium-catalyzed cyclization of dimethyl-substituted allene possessing amino functionality with aryl iodides efficiently proceeded in the presence of diisopropylethylamine to give 2,2-dimethyl-3-aryl-3-pyrrolines. Under an atmospheric pressure of carbon monoxide, 3-aroyl-3-pyrrolines are provided in good yield.

  • Rhodium complex-catalyzed Pauson-Khand-type reaction with aldehydes as a CO source

    T Shibata, N Toshida, K Takagi

    JOURNAL OF ORGANIC CHEMISTRY   67 ( 21 ) 7446 - 7450  2002.10

     View Summary

    With aldehydes as a CO source under solvent-free conditions, rhodium complex efficiently catalyzed an intramolecular carbonylative alkene-alkyne coupling (Pauson-Khand-type reaction) and various bicyclic enones were obtained in high yield. Experiments under argon flow and a C-13-labeling experiment suggested that almost no free carbon monoxide was generated in this reaction, When noncationic rhodium complex with chiral phosphine was used as a chiral catalyst, the reaction proceeded enantioselectively to give various chiral cyclopentenones in up to 90% ee under solvent-free conditions.

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  • Iridium complex-catalyzed enantioselective intramolecular [4+2] cycloaddition of dieneynes

    T Shibata, K Takasaku, Y Takesue, N Hirata, K Takagi

    SYNLETT   2002 ( 10 ) 1681 - 1682  2002.10

     View Summary

    A catalytic and highly enantioselective intramolecular [4+2] cycloaddition of dieneynes was achieved by use of chiral iridium complex prepared in situ from [IrCl(cod)](2) and BDPP [2,4-bis(diphenylphosphino)pentane]. The reaction proceeded in refluxed tent-butyl acetate to give chiral cyclohexa-1,4-dienes in very high enantiomeric excess.

  • Ir and Rh complex-catalyzed intramolecular alkyne-alkyne couplings with carbon monoxide and isocyanides

    T Shibata, K Yamashita, E Katayama, A Takagi

    TETRAHEDRON   58 ( 43 ) 8661 - 8667  2002.10

     View Summary

    Intramolecular [2+2+1] cycloaddition of diynes with carbon monoxide was catalyzed by Vaska's complex (lrCl(CO)(PPh3)(2)) or IrCI(cod)(dppp), and cyclopentadienones were obtained in good to high, yields. The first catalytic synthesis of iminocyclopentadienes was achieved by portionwise additions of isocyanides to a solution of diynes and Rh catalyst ([RhCl(cod)](2)). (C) 2002 Elsevier Science Ltd. All rights reserved.

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    50
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  • Asymmetric automultiplication of chiral compounds by asymmetric autocatalysis

    K Soai, Sato, I, T Shibata

    JOURNAL OF SYNTHETIC ORGANIC CHEMISTRY JAPAN   60 ( 7 ) 668 - 678  2002.07

     View Summary

    Asymmetric automultiplication of chiral compounds by asymmetric autocatalysis is realized for the first time where a chiral product acts as a chiral catalyst for its own production. Practically perfect asymmetric autocatalysis (&gt;99%, &gt;99.5% ee) is attained using pyrimidyl alkanol as an asymmetric autocatalyst in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde. Moreover, asymmetric autocatalyst with very low ee enhances its ee significantly up to &gt; 99.5% ee during the automultiplication without the assistance of any other chiral auxiliaries. Amino acids and [6]helicene with very low ee which are produced by asymmtric photolysis and photosynthesis using circularly polarized light (CPL) serve as chiral initiators of asymmetric autocatalysis, and pyrimidyl alkanol with high ee is obtained. Inorganic chiral crystals such as quartz and sodium chlorate also work as chiral initiators. These results correlate for the first time the proposed origins of chirality of organic compounds such as CPL and quartz with the chirality of organic compounds with very high ee.

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    15
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  • Catalytic Pauson-Khand-type reaction using aldehydes as a CO source

    T Shibata, N Toshida, K Takagi

    ORGANIC LETTERS   4 ( 9 ) 1619 - 1621  2002.05

     View Summary

    Rhodium complex-catalyzed carbonylative alkene-alkyne coupling proceeds using aldehydes as a CO source. Cinnamaldehyde is the best CO donor, and various cyclopentenones were provided in high isolated yields by a solvent-free system.

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    159
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  • Asymmetric Diels-Alder reactions catalyzed by a triflic acid activated chiral oxazaborolidine

    EJ Corey, T Shibata, TW Lee

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   124 ( 15 ) 3808 - 3809  2002.04

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    250
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  • Asymmetric autocatalysis of pyrimidyl alkanol induced by optically active 1,1 '-binaphthyl, an atropisomeric hydrocarbon, generated from spontaneous resolution on crystallization

    Sato, I, S Osanai, K Kadowaki, T Sugiyama, T Shibata, K Soai

    CHEMISTRY LETTERS   2002 ( 2 ) 168 - 169  2002.02

     View Summary

    An atropisomeric hydrocarbon, (R)-1,1'-binaphthyl, acts as a chiral initiator of asymmetric autocatalysis of pyrimidyl alkanol in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde to afford (S)-5-pyrimidyl alkanol 2 with 96% ee. On the other hand, in the presence of (S)-1,1'-binaphthyl, the reaction affords (R)-2 with 94% ee.

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    31
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  • Highly enantioselective asymmetric autocatalysis of pyrimidin-5-yl alkanol induced by chiral 1,3-disubstituted hydrocarbon allenes

    Sato, I, Y Matsueda, K Kadowaki, S Yonekubo, T Shibata, K Soai

    HELVETICA CHIMICA ACTA   85 ( 10 ) 3383 - 3387  2002

     View Summary

    1,3-Disubstituted chiral allenes without any heteroatoms act as chiral initiators in the addition of (i-Pr)(2)Zn to pyrimidine-5-carbaldehyde to afford. in combination with the subsequent asymmetric autocatalysis, chiral pyrimidin-5-yl alkanols with up to 98% ee. The absolute configuration of the pyrimidin-5-yl alkanol formed depend on that of the chiral allene.

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  • Asymmetric Autocatalysis: Automultiplication, Amplification of Chirality and the Origin of Chiral Homogeneity of Organic Molecules

    My Favorite Organic Synethesis,モ edited by The Society of Synthetic Organic Chemistry    2002

  • Palladium-catalyzed synthesis of biaryls from arylzinc compounds using N-chlorosuccinimide or oxygen as an oxidant

    KM Hossain, T Kameyama, T Shibata, K Takagi

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   74 ( 12 ) 2415 - 2420  2001.12

     View Summary

    In the presence of a catalytic amount of Pd2+ or Pd-0, oxidative homo-coupling of arylzinc compounds was achieved by the use of N-chlorosuccinimide (NCS) or O-2 as an oxidant. Different reaction pathways were involved in the catalytic reactions depending on the oxidants; NCS or O-2 probably oxidized I- or Pd-0 to I+ or Pd2+, respectively. This reaction disclosed a new and facile synthetic method of biaryls from aryl halides or arenes via arylzinc intermediates.

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    23
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  • Iridium complex catalyzed carbonylative alkyne-alkyne coupling for the synthesis of cyclopentadienones

    T Shibata, K Yamashita, H Ishida, K Takagi

    ORGANIC LETTERS   3 ( 8 ) 1217 - 1219  2001.04

     View Summary

    Catalytic carbonylative alkyne-alkyne coupling proceeds using iridium-phosphine complexes under carbon monoxide at atmospheric pressure or a partial pressure of 0.2 atm. This reaction provides various cyclopentadienones in high isolated yields.

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  • Asymmetric autocatalysis - Discovery and development

    K Soai, T Shibata, Sato, I

    NIPPON KAGAKU KAISHI   2001 ( 3 ) 141 - 149  2001.03

     View Summary

    The asymmetric autocatalysis is an enantioselective synthesis where the asymmetric catalyst and the product possess the same structure and the same absolute configuration. We disclosed chiral alpha -isopropyl-3-pyridinemethanols, alpha -isopropyl-5-pyrimidinemethanols, and alpha -isopropyl-3-quino- linemethanols operate as asymmetric autocatalysts in the enantioselective additions of i-Pr2Zn to 3-pyridinecarbaldehyde, 5-pyrimidinecarbaldehyde and 3-quinolinecarbaldehyde, respectively. Especially, practically perfect asymmetric autocatalysis ( &gt; 99% yield and &gt; 99.5%e.e.) is attained by using 2- (3,3-dimethyl-1-butynyl)-alpha -isopropyl-5-pyrimidinemethanol as an asymmetric autocatalyst. Moreover, consecutive asymmetric autocatalytic reaction enables alpha -isopropyl-5-primidine- and alpha -isopropyl-3-quinolinemethanols as well as 5-(1-hydroxy-2-methylpropyl) pyridine-3-carboxamides with extremely low e.e. to automultiply with dramatic amplification of e.e. without any assistance of other chiral auxiliaries.
    It was also found that various chiral compounds can operate as chiral initiators in the enantioselective addition of i-Pr2Zn to 5-pyrimidinecarbaldehydes and alpha -isopropyl-5-pyrimidinemethanols with high e.e. were obtained. For example, in the presence of L-leucine with 2 %e.e., asymmetric autocatalysis affords an (R)-alpha -isopropyl-5-pyrimidinemethanol with high e.e. It is known that asymmetric degradation of racemic leucine using circularly polarized light (CPL) gives chiral leucine (ca. 2 %e.e.). Thus, asymmetric autocatalysis with amplification of e.e. serves as a correlation between CPL and highly enantiomerically enriched organic molecules. Moreover, enantiomorphic inorganic crystals such as quartz (SiO2) and sodium chlorate (NaClO3) can be utilized as chiral initiators and an alpha -isopropyl-5-pyrimidinemethanols with high e.e. was obtained in high yields.

  • Unusual chemoselective addition of diisopropylzinc to 2,2 '-bipyridine-5,5 '-dicarbonyl compounds in the 2-position and autoxidative reconversion with carbon-carbon bond cleavage

    S Tanji, T Shibata, Sato, I, K Soai

    JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1   ( 3 ) 217 - 218  2001

     View Summary

    Unusual chemoselective addition of diisopropylzinc to the 2-position of 2,2'-bipyridine-5,5'-dicarbonyl compounds affords the adducts with a quaternary carbon, and autoxidation of the adducts reconverts them into the initial compounds with carbon-carbon bond cleavage.

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    6
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  • Asymmetric autocatalysis and the origin of chiral homogeneity in organic compounds

    K Soai, Sato, I, T Shibata

    CHEMICAL RECORD   1 ( 4 ) 321 - 332  2001

     View Summary

    The discovery and development of asymmetric autocatalysis, in which the structures of the chiral catalyst and the chiral product are the same, are described. Chiral 5-pyrimidyl, 3-quinolyl, and 5-carbamoyl-3-pyridyl alkanols act as highly enantioselective asymmetric autocatalysts in the enantioselective addition of diisopropylzinc to the corresponding aldehydes, such as pyrimidine-5-carbaldehyde. 2-Alkynyl-5-pyrimidyl alkanol with an enantiomeric excess (ee) of &gt;99.5% automultiplies practically perfectly as an asymmetric autocatalyst in a yield of &gt;99% and &gt;99.5% ee. Asymmetric autocatalysis with an amplification of ee has thus been realized. Consecutive asymmetric autocatalysis starting with chiral 2-alkynylpyrimidyl alkanol of only 0.6% ee amplifies its ee significantly, and yields itself as the product with &gt;99.5% ee. The reaction of pyrimidine-5-carbaldehyde and diisopropylzinc in the presence of chiral initiators with low ee's, such as secondary alcohol, amine, carboxylic acid, mono-substituted [2.2]paracyclophane, and chiral primary alcohols due to deuterium substitution, regulates the absolute configuration of the resulting pyrimidyl alkanols, and the ee of the resulting pyrimidyl alkanol is much higher than that of the chiral initiator. Leucine and [6]helicene with very low ee's, which are known to be induced by circularly polarized light (CPL), also serve as chiral initiators to produce pyrimidyl alkanol with higher ee's. Overall, the process represents the first correlation between the chirality of CPL and an organic compound with very high ee. Chiral inorganic crystals, such as quartz and sodium chlorate, act as chiral inducers in the asymmetric autocatalysis of pyrimidyl alkanol. The process correlates for the first time ever the chirality of inorganic crystals with an organic compound with very high ee. (C) 2001 The Japan Chemical journal Forum and John Wiley Sons, Inc.

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  • Asymmetric induction by helical hydrocarbons: [6]- and [5]helicenes

    Sato, I, R Yamashima, K Kadowaki, J Yamamoto, T Shibata, K Soai

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   40 ( 6 ) 1096 - +  2001

  • Inter- and intramolecular carbonylative alkyne-alkyne coupling reaction mediated by cobalt carbonyl complex

    T Shibata, K Yamashita, K Takagi, T Ohta, K Soai

    TETRAHEDRON   56 ( 47 ) 9259 - 9267  2000.11

     View Summary

    Inter- and intramolecular carbonylative coupling reactions proceed between alkynes possessing diphenylallylsilyl group mediated by dicobalt carbonyl complex under argon atmosphere. This coupling reaction directly provides various mono- and bicyclic cyclopentadienones in high yields. (C) 2000 Elsevier Science Ltd. All rights reserved.

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  • Asymmetric autocatalysis of 5-carbamoyl-3-pyridyl alkanols with amplification of enantiomeric excess

    S Tanji, Y Kodaka, A Ohno, T Shibata, Sato, I, K Soai

    TETRAHEDRON-ASYMMETRY   11 ( 21 ) 4249 - 4253  2000.11

     View Summary

    5-Carbamoyl-3-pyridyl alkanols with low e.e. act as asymmetric autocatalysts in the consecutive asymmetric autocatalytic addition of diisopropylzinc to 5-carbamoyl-3-pyridinecarbaldehydes. The e.e, of pyridyl alkanol amplified up to 88% e.e. without the need for any other chiral auxiliary. (C) 2000 Elsevier Science Ltd. An rights reserved.

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    38
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  • Iridium-chiral diphosphine complex catalyzed highly enantioselective Pauson-Khand-type reaction

    T Shibata, K Takagi

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   122 ( 40 ) 9852 - 9853  2000.10

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    199
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  • A new synthetic method to biaryls from arylzinc iodides using N-chlorosuccinimide and a catalytic amount of palladium

    KM Hossain, T Shibata, K Takagi

    SYNLETT   2000 ( 8 ) 1137 - 1138  2000.08

     View Summary

    Home-coupling reactions of aryl- or alkynylzinc iodides were achieved by the use of N-chlorosuccinimide as an oxidant of zinc compounds in the presence of a catalytic amount of Pd.

    DOI

  • Enantioselective automultiplication of chiral molecules by asymmetric autocatalysis

    K Soai, T Shibata, Sato, I

    ACCOUNTS OF CHEMICAL RESEARCH   33 ( 6 ) 382 - 390  2000.06

     View Summary

    Asymmetric autocatalysis is a process of automultiplication of a chiral compound in which chiral product acts as a chiral catalyst for its own production. The discovery and the development of asymmetric autocatalysis of pyrimidyl-, quinolyl-, and pyridyl-alkanols are described in the enantioselective additions of diisopropylzinc to the corresponding nitrogen-containing aldehydes. (Alkynylpyrimidyl)alkanols automultiply with a yield of over 99% and over 99.5% ee. Asymmetric autocatalysts with extremely low ee's automultiply with significant amplification of ee's without the need for any other chiral auxiliaries. Small enantiomeric imbalances of chiral molecules induced by physical factors can be amplified by the present asymmetric autocatalysis.

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  • Highly enantioselective addition of diethylzinc to N-diphenylphosphinylimines using dendritic chiral ligands with hydrocarbon backbones

    Sato, I, R Kodaka, T Shibata, Y Hirokawa, N Shirai, K Ohtake, K Soai

    TETRAHEDRON-ASYMMETRY   11 ( 11 ) 2271 - 2275  2000.06

     View Summary

    Chiral dendrimers bearing three or six chiral B-amino alcohols on the hyperbranched hydrocarbon chain-ends act as efficient chiral ligands for the enantioselective addition of diethylzinc to N-diphenyl-phosphinylimines to afford enantiomerically enriched N-diphenylphosphinylamines with up to 94% e.e. (C) 2000 Elsevier Science Ltd. All rights reserved.

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    35
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  • Synthesis of chiral dendrimers with a hydrocarbon backbone and application to the catalytic enantioselective addition of dialkylzincs to aldehydes

    Sato, I, T Shibata, K Ohtake, R Kodaka, Y Hirokawa, N Shirai, K Soai

    TETRAHEDRON LETTERS   41 ( 17 ) 3123 - 3126  2000.04

     View Summary

    Chiral dendrimers with three or six beta-amino alcohols on hyperbranched hydrocarbon chain-ends were synthesized. These macromolecules can act as chiral catalysts for the enantioselective addition of dialkylzincs to aldehydes. The corresponding secondary alcohols are obtained in high enantiomeric excess (up to 86% e.e.). (C) 2000 Elsevier Science Ltd. All rights reserved.

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    56
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  • Nucleophilic additions of arylzinc compounds to aldehydes mediated by CrCl3: Efficient and facile synthesis of functionalized benzhydrols, 1(3H)-isobenzofuranones, benzyl alcohols, or diaryl ketones

    Y Ogawa, A Saiga, M Mori, T Shibata, K Takagi

    JOURNAL OF ORGANIC CHEMISTRY   65 ( 4 ) 1031 - 1036  2000.02

     View Summary

    In the presence of a stoichiometric amount of CrCl3 and trimethylchlorosilane (TMSCl), nucleophilic addition of arylzinc compounds Ic-h to arylaldehydes 2a,b,g smoothly proceeded at room temperature to yield corresponding benzhydrols 4a-f in good yields. From arylzinc compounds la,b, 3-aryl-1(3H)-isobenzofuranones 3a-f were given by the CrCl3-mediated reaction with arylaldehydes 2a-f. Diaryl ketones 5a-e were obtained in good yields by the addition of excess amount of benzaldehyde as an oxidant to the resulting solution after the CrCl3-mediated reaction between arylzinc compounds Ic-p and arylaldehydes 2b,g was completed. In the nucleophilic additions of arylzinc compounds la,d,f to alkyladehydes 6b-f, the treatment of arylzinc compounds with CrCl3 was required prior to the addition of the aldehydes in order to prevent the fast protodezincation of arylzinc compounds by the enolizable aldehydes. In these CrCl3-mediated nucleophilic additions of arylzinc compounds to aldehydes, arylchromium(III) species are probably reactive intermediates.

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    31
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  • Synthesis of chiral alpha-acetoxy-(N)under-bar-acetylamides from chiral pyrimidylalkanols by the oxidative cleavage of pyrimidine ring

    S Tanji, Y Kodaka, T Shibata, K Soai

    HETEROCYCLES   52 ( 1 ) 151 - 158  2000.01

     View Summary

    Acetates of chiral 5-pyrimidylalkanols are transformed into chiral a acetoxy-N-acetylamides and alpha-acetoxyamides without racemization in high total yields by the oxidative cleavage of pyrimidine ring using ruthenium tetroxide.

  • Highly enantioselective catalytic isopropenylation of aldehydes using diisopropenylzinc

    T Shibata, K Nakatsui, K Soai

    INORGANICA CHIMICA ACTA   296 ( 1 ) 33 - 36  1999.12

     View Summary

    Diisopropenylzinc adds highly enantioselectively to various aldehydes in the presence of a catalytic amount of chiral amino alcohols to give enantiomerically enriched allyl alkanols with up to 92% e.e. (C) 1999 Elsevier Science S.A. All rights reserved.

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    32
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  • d- and l-quartz-promoted highly enantioselective synthesis of a chiral organic compound

    K Soai, S Osanai, K Kadowaki, S Yonekubo, T Shibata, Sato, I

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   121 ( 48 ) 11235 - 11236  1999.12

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  • Highly enantioselective addition of dialkylzincs to aromatic aldehydes using 1-phenyl-2-(1-pyrrolidinyl)-1-propanol as a chiral catalyst

    K Soai, T Konishi, T Shibata

    HETEROCYCLES   51 ( 6 ) 1421 - +  1999.06

     View Summary

    (1S,2R)- and (1R,2S)-1-phenyl-2-(1-pyrrolidinyl)-1-propanol catalyzes the enantioselective addition of dialkylzincs to aromatic aldehydes to afford enantiomerically enriched aromatic sec-alcohols with up to 92% enantiomeric excess.

  • Enantioselective alkylation of N-diphenylphosphinylimine with dialkylzincs using copolymerized chiral ligands

    T Suzuki, N Narisada, T Shibata, K Soai

    POLYMERS FOR ADVANCED TECHNOLOGIES   10 ( 1-2 ) 30 - 38  1999.01

     View Summary

    Enantioselective alkylation of N-diphenylphosphinylimine with dialkylzincs using monomeric chiral amino alcohols and copolymerized chiral amino alcohols as chiral ligands afforded N-diphenylphosphinylamines with high enantiomeric excess (EE). Among monomeric chiral ligands, N-vinylbenzylephedrine was the most highly enantioselective to afford the corresponding N-diphenylphosphinylamine with 95% EE. Chiral monomeric amino alcohols were copolymerized with styrene in the presence of crosslinking reagents such as divinylbenzene. The enantioselectivities of copolymerized chiral ligands were also high (up to 89% EE). Copolymerized chiral ligand was easily separated from the reaction mixture by filtration and was reused without considerable decrease in the enantioselectivity. Copolymerized chiral ligands prepared using crosslinking reagents with methylene spacers also showed high enantioselectivities, giving N-diphenylphosphinylamine with up to 90% EE. Regarding of the effect of solvent, aromatic hydrocarbons (toluene and benzene) and diethyl ether are appropriate. The effect of a spacer introduced on the nitrogen atom of the amino alcohol was also examined. (C) 1999 John Wiley & Sons, Ltd.

    DOI

  • Practically perfect asymmetric autocatalysis with (2-alkynyl-5-pyrimidyl)alkanols

    T Shibata, S Yonekubo, K Soai

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   38 ( 5 ) 659 - 661  1999

    DOI

  • Amplification of a slight enantiomeric imbalance in molecules based on asymmetric autocatalysis: The first correlation between high enantiomeric enrichment in a chiral molecule and circularly polarized light

    T Shibata, J Yamamoto, N Matsumoto, S Yonekubo, S Osanai, K Soai

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   120 ( 46 ) 12157 - 12158  1998.11

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  • Direct synthesis of cyclopentadienones by cobalt carbonyl-mediated carbonylative alkyne-alkyne coupling reaction

    T Shibata, T Ohta, K Soai

    TETRAHEDRON LETTERS   39 ( 32 ) 5785 - 5788  1998.08

     View Summary

    Dicobalt carbonyl complex mediates an intermolecular carbonylative coupling reaction between alkynylsilanes, The reaction proceeds under atmospheric pressure of argon and directly provides free cyclopentadienones in high yields (up to 99%). (C) 1998 Elsevier Science Ltd. All rights reserved.

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    16
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  • An enantioselective Baylis-Hillman reaction catalyzed by chiral phosphines under atmospheric pressure

    T Hayase, T Shibata, K Soai, Y Wakatsuki

    CHEMICAL COMMUNICATIONS   1998 ( 12 ) 1271 - 1272  1998.06

     View Summary

    2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) catalyzes the enantioselective Baylis-Hillman reaction between pyrimidine- 5-carbaldehydes and acrylates to provide chiral alpha-methylene beta-hydroxy esters in up to 44% ee under atmospheric pressure.

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    110
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  • A catalytic and enantioselective cyclopropylation of aldehydes using dicyclopropylzinc

    T Shibata, H Tabira, K Soai

    JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1   1998 ( 2 ) 177 - 178  1998.01

     View Summary

    Enantioselective cyclopropylation of various aldehydes proceeds using dicyclopropylzine in the presence of a catalytic amount of chiral amino alcohol or thiophosphoramidate with Ti(OPri)(4) to provide enantiomerically enriched cyclopropyl alkanols (up to 96.6% ee).

  • Asymmetric synthesis of 3-quinolylalkylamine by enantioselective alkylation of N-diphenylphosphinyl-3-quinolylimine using chiral beta-amino alcohols

    T Hayase, S Osanai, T Shibata, K Soai

    HETEROCYCLES   48 ( 1 ) 139 - 144  1998.01

     View Summary

    Chiral N-diphenylphosphinyl-3-quinolylamines (DPP amines) with up to 74. 9% e.e. were obtained by the enantioselective alkylation using dialkylzincs in the presence of various chiral amino alcohols. The acidic hydrolysis of the chiral DPP amine afforded optically active chiral 3-quinolylamine without racemization.

  • Stereospecific transformation of a chiral pyrimidyl alkanol into L-valine

    K Soai, S Tanji, Y Kodaka, T Shibata

    ENANTIOMER   3 ( 3 ) 241 - 243  1998

     View Summary

    A chiral pyrimidyl alkanol with high enantiomeric excess is transformed into L-valine with high e.e. by a notable oxidative cleavage of pyrimidine ring using ruthenium oxide as a key step. This process would correlate natural alpha-amino acids with a chiral pyrimidyl alkanol, which is reported to possess an asymmetric autocatalytic activity with amplification of e.e.

  • Chiral amino alcohols bound to diimines, diamines and dendrimers as chiral ligands for the enantioselective ethylation of N-diphenylphosphinylimines

    T Suzuki, Y Hirokawa, K Ohtake, T Shibata, K Soai

    TETRAHEDRON-ASYMMETRY   8 ( 24 ) 4033 - 4040  1997.12

     View Summary

    Chiral diimines, diamines and dendrimers possessing 2, 4 and 8 ephedrine derivatives are utilized as chiral ligands for the enantioselective addition of diethylzinc to N-diphenylphosphinylimines to afford enantiomerically enriched N-diphenylphosphinylamines in up to 93% e.e. (C) 1997 Elsevier Science Ltd. All rights reserved.

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  • Asymmetric self-replication of chiral 1,2-amino alcohols by highly enantioselective autoinductive reduction

    T Shibata, T Takahashi, T Konishi, K Soai

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION IN ENGLISH   36 ( 22 ) 2458 - 2460  1997.12

  • Asymmetric synthesis of various chiral 5-pyrimidyl-alkanols by the enantioselective alkylation of pyrimidine-5-carbaldehydes with dialkylzincs in the presence of chiral amino alcohols

    T Shibata, T Hayase, Y Aiba, H Tabira, K Soai

    HETEROCYCLES   46   235 - 240  1997.12

     View Summary

    (1 (S) under bar, 2 (R) under bar)-(N) under bar,(N) under bar-Dibutylnorephedrine catalyzes the enantioselective addition of dialkylzincs to various pyrimidine-5-carbaldehydes. Ethylation and butylation proceed with high enantioselectivities (up to 94% e.e.) to give optically active secondary 5-pyrimidyl alkanols.

  • Design of chiral catalysis and asymmetric autocatalysis for the enantioselective additions of organozinc reagents

    K Soai, T Shibata

    JOURNAL OF SYNTHETIC ORGANIC CHEMISTRY JAPAN   55 ( 11 ) 994 - 1005  1997.11

     View Summary

    Diphenyl(1-methylpyrrolidin-2-yl)methanol (DPMPM) and N,N-dibutylnorephedrine (DBNE) are highly enantio- and chemoselective chiral catalysts for the addition of dialkylzincs to various aldehydes, affording sec-alcohols with high enantiomeric excesses. Heterogeneous chiral catalyst supported on polystyrene is also highly enantioselective. Pyrimidyl and quinolyl alkanols me asymmetric autocatalysts with amplification of enantiomeric excess in the enantioselective isopropylatian of aldehydes. Enantioselective addition of dialkylzincs to N-diphenylphosphinylimines and conjugate addition to enones me performed using N,N-dialkylnorephedrines.

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  • Enantioselective addition of dialkylzincs to N-diphenylphosphinylimines using polymer-supported N,N-dialkylnorephedrines as chiral ligands

    T Suzuki, T Shibata, K Soai

    JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1   1997 ( 18 ) 2757 - 2760  1997.09

     View Summary

    Chiral N,N-dialkylnorephedrines supported on polystyrene resin catalyse the enantioselective addition of dialkylzincs to N-diphenylphosphinylimine, affording optically active N-diphenylphosphinylamines with high enantiomeric excess, The influence on the enantioselectivity of the carbon-chain spacer between the chiral function and polymer resin has been examined. Reaction temperature- and solvent-dependency on the chiral polymer-catalysed reaction has also been examined.

  • Asymmetric synthesis of optically active fluorine-containing alcohols by the catalytic enantioselective alkylation of aldehydes

    T Hayase, T Sugiyama, M Suzuki, T Shibata, K Soai

    JOURNAL OF FLUORINE CHEMISTRY   84 ( 1 ) 1 - 5  1997.08

     View Summary

    Optically active fluorine-containing alcohols with up to 97% enantiomeric excess were synthesized by the enantioselective addition of dialkylzincs to fluorine-containing aldehydes using chiral beta-aminoalcohol catalysts such as N,N-dibutylnorephedrine (DBNE, 2d), 2-morpholino-1-phenyl-1-propanol (2g, MOPEP) and diphenyl (1-methylpyrrolidin-2-yl)methanol (3, DPMPM). (C) 1997 Elsevier Science S.A.

    DOI

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    21
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  • One-pot asymmetric autocatalytic reaction with remarkable amplification of enantiomeric excess

    T Shibata, T Hayase, J Yamamoto, K Soai

    TETRAHEDRON-ASYMMETRY   8 ( 11 ) 1717 - 1719  1997.06

     View Summary

    A trace amount (ca. 3 mg) of 2-methylpyrimidyl alkanol with only a slight enantiomeric excess (0.2-0.3% e.e.) was auto-multiplied with dramatic amplification of enantiomeric excess (up to ca. 90% e.e.) in one-pot asymmetric autocatalytic reaction using diisopropylzinc and 2-methylpyrimidine-5-carbaldehyde. (C) 1997 Elsevier Science Ltd.

    DOI

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    69
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  • Enantioselective synthesis of chiral 5-carbamoyl-3-pyridyl alcohols by asymmetric autocatalytic reaction

    T Shibata, H Morioka, S Tanji, T Hayase, Y Kodaka, K Soai

    TETRAHEDRON LETTERS   37 ( 48 ) 8783 - 8786  1996.11

     View Summary

    A catalytic amount of a chiral zinc alkoxide of 5-carbamoyl-3-pyridyl alkyl alcohol catalyzes an enantioselective alkylation of 5-carbamoylpyridine-3-carbaldehyde by diisopropylzinc to afford itself in up to 86% e.e. with the same configuration as the catalyst. Enantioselectivity is dependent on the structure of substituents on the nitrogen atom of the amide. Copyright (C) 1996 Elsevier Science Ltd

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  • Asymmetric synthesis of chiral diols by the catalytic enantioselective dialkylation of tere-, iso-, and phthaldehydes and by a catalytic enantioselective autoinductive reaction

    K Soai, Y Inoue, T Takahashi, T Shibata

    TETRAHEDRON   52 ( 42 ) 13355 - 13362  1996.10

     View Summary

    Optically pure aromatic diols were synthesized by the highly enantioselective dialkylation of aromatic dialdehydes with dialkylzincs in the presence of a catalytic amount of chiral aminoalcohol 1 or chiral thiophosphoramide alcohol 2 with Ti(O-i-Pr)(4). The chiral titanium(IV) alkoxide of 4b, a diisopropylated product of isophthalaldehyde, catalyzed the addition of diisopropylzinc to isophthalaldehyde to gave a chiral zinc alkoxide of 4b with the same configuration by an enantioselective autoinductive reaction (up to 44% e.e.). Copyright (C) 1996 Elsevier Science Ltd

    DOI

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  • N-alkyl-N-vinylbenzylnorephedrines and their copolymers as chiral ligands for the highly enantioselective ethylation of N-diphenylphosphinylimine

    T Suzuki, N Narisada, T Shibata, K Soai

    TETRAHEDRON-ASYMMETRY   7 ( 9 ) 2519 - 2522  1996.09

     View Summary

    Enantioselective addition of diethylzinc to N-diphenylphosphinylimine in the presence of a stoichiometric amount of N-alkyl-N-vinylbenzylnorephedrines and their copolymers as chiral ligands affords optically active N-diphenylphosphinylamine with up to 95% e.e. Copyright (C) 1996 Published by Elsevier Science Ltd

    DOI

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    46
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  • Asymmetric synthesis of N-(diphenylphosphinyl)-ferrocenylamine by the enantioselective alkylation of ferrocenylimine

    T Hayase, Y Inoue, T Shibata, K Soai

    TETRAHEDRON-ASYMMETRY   7 ( 9 ) 2509 - 2510  1996.09

     View Summary

    Optically active N-(diphenylphosphinyl)ferrocenylamines with good to high e.e.'s were obtained by the enantioselective addition of dialkylzincs to ferrocenyl-diphenylphosphinylimine in the presence of chiral beta-aminoalcohols The subsequent hydrolysis afforded a chiral ferrocenylamine without racemization. Copyright (C) 1996 Published by Elsevier Science Ltd

    DOI

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    38
    Citation
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  • Asymmetric autocatalytic reaction of 3-quinolylalkanol with amplification of enantiomeric excess

    T Shibata, K Choji, T Hayase, Y Aizu, K Soai

    CHEMICAL COMMUNICATIONS   1996 ( 10 ) 1235 - 1236  1996.05

     View Summary

    The enantiomeric excess of a chiral 3-quinolylalkanol increases from 8.9 to 88.1% by a series of asymmetric autocatalytic alkylations of quinoline-3-carbaldehyde using diisopropylzinc.

    DOI

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    78
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  • Highly enantioselective synthesis of a chiral 3-quinolylalkanol by an asymmetric autocatalytic reaction

    T Shibata, K Choji, H Morioka, T Hayase, K Soai

    CHEMICAL COMMUNICATIONS   1996 ( 6 ) 751 - 752  1996.03

     View Summary

    A catalytic amount of a chiral zinc alkoxide of 2-methyl-1-(3-quinolyl)propan-1-ol catalyses the enantioselective alkylation of quinoline-3-carbaldehyde by diisopropylzine to afford 2-methyl-1-(3-quinolyl)propan-1-ol with the same configuration in high ee (up to 94%).

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  • Highly enantioselective catalytic asymmetric automultiplication of chiral pyrimidyl alcohol

    T Shibata, H Morioka, T Hayase, K Choji, K Soai

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   118 ( 2 ) 471 - 472  1996.01

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  • 生成物が関与する不斉合成反応-不斉自己触媒反応への新展開-

    化学   51/,62  1996

  • 自己増殖するキラル分子-高選択的な不斉自己触媒反応の開発-

      10/,36  1996

  • ASYMMETRIC AUTOCATALYSIS AND AMPLIFICATION OF ENANTIOMERIC EXCESS OF A CHIRAL MOLECULE

    K SOAI, T SHIBATA, H MORIOKA, K CHOJI

    NATURE   378 ( 6559 ) 767 - 768  1995.12

     View Summary

    THE homochirality of natural amino acids and sugars remains a puzzle for theories of the chemical origin of life(1-18). In 1953 Frank(7) proposed a reaction scheme by which a combination of autocatalysis and inhibition in a system of replicating chiral molecules can allow small random fluctuations in an initially racemic mixture to tip the balance to yield almost exclusively one enantiomer. Here we show experimentally that autocatalysis in a chemical reaction can indeed enhance a small initial enantiomeric excess of a chiral molecule. When a 5-pyrimidyl alkanol with a small (2%) enantiomeric excess is treated with diisopropylzinc and pyrimidine-5-carboxaldehyde, it undergoes an autocatalytic reaction to generate more of the alkanol. Because the reaction involves a chiral catalyst generated from the initial alkanol, and because the catalytic step is enantioselective, the enantiomeric excess of the product is enhanced, This process provides a mechanism by which a small initial imbalance in chirality can become overwhelming.

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    896
    Citation
    (Scopus)
  • INTRAMOLECULAR AND INTERMOLECULAR ALLENE-ALKYNE COUPLING REACTIONS BY THE USE OF FE(CO)(4)(NME(3))

    T SHIBATA, Y KOGA, K NARASAKA

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   68 ( 3 ) 911 - 919  1995

     View Summary

    Intramolecular allene-alkyne coupling reactions proceed in the presence of Fe(CO)(4)(NMe(3)) under photoirradiation conditions to provide various bicyclic dienones through eta(3)-allyl iron complexes. Various 4-methylene-2-cyclopenten-1-ones could be prepared by intermolecular allene-alkyne coupling reaction under the same reaction conditions.

    DOI

  • CONVERSION OF 1-(OMEGA-ALKYNYL)-1,2-PROPADIENYL SULFIDES TO BICYCLIC DIENONES BY THE USE OF IRON CARBONYL COMPLEX

    K NARASAKA, T SHIBATA

    CHEMISTRY LETTERS   1994 ( 2 ) 315 - 318  1994.02

     View Summary

    1-(omega-Alkenyl)-1,2-propadienyl sulfide reacts with Fe(CO)(4)(NMe(3)) under photo irradiation conditions and a cyclized and carbonylated eta(3)-allyl mononuclear iron complex is isolated. On the other hand, the reaction of 1-(omega-alkynyl)-1,2-propadienyl sulfides and Fe(CO)(4)(NMe(3)) also proceeds by photo irradiation to give various bicyclic dienones through the eta(3)-allyl iron complex.

    DOI

  • REACTIONS OF 1,2-PROPADIENYL SULFIDES WITH ALDEHYDES AND ACETALS CATALYZED BY BF3.OET2

    K NARASAKA, T SHIBATA, Y HAYASHI

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   65 ( 10 ) 2825 - 2830  1992.10

     View Summary

    Ene reaction proceeds between 1-alkyl-1,2-propadienyl sulfides and aldehydes in the presence of BF3 . OEt2 to afford 1,3-dienes possessing an alkylthio group. On the other hand, the reactions of 1-silyl-1,2-propadienyl sulfides with aldehydes or their dimethylacetals give aldol-type addition products, alpha-methylene acylsilanes.

    DOI

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    4
    Citation
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  • ACID-PROMOTED REACTIONS OF SCHIFF-BASES WITH KETENE DITHIOACETAL, VINYL SULFIDES, AND 1,2-PROPADIENYL SULFIDES

    K NARASAKA, T SHIBATA, Y HAYASHI

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   65 ( 5 ) 1392 - 1396  1992.05

     View Summary

    Several types of addition reactions proceed between Schiff's bases and olefinic nucleophiles containing an alkylthio substituent. Ketene dithioacetal or 2-(methylthio)allylsilane reacts with Schiff's bases in the presence of trifluoromethanesulfonic acid to afford beta-amino acid equivalents or homoallylic amines, respectively. On the other hand, ene reaction proceeds between 1-alkyl-1,2-propadienyl sulfides and Schiff's bases by treatment with AlCl3, giving 1,3-dienes.

    DOI

  • BF3・OEt2 Catalyzed [4+2] Cycloaddition Reactions of N-Aryl Schiff's Bases with 1-Alkenyl, 1,2-Propadienyl, and 1-Alkylnyl Sulfides

    K. Narasaka, T. Shibata

    Heterocycles   35   1039 - 1053  1991

  • ENE REACTION OF ALLENYL SULFIDES WITH ALDEHYDES AND SCHIFFS BASES CATALYZED BY LEWIS-ACIDS

    Y HAYASHI, T SHIBATA, K NARASAKA

    CHEMISTRY LETTERS   1990 ( 9 ) 1693 - 1696  1990.09

    DOI

▼display all

Books and Other Publications

  • Asymmetric additions using diorganozincs

    K. Soai, T. Shibata

    Organozinc Reagents: A Pratical Approach  1999

  • 不斉自己触媒反応-自己増殖するキラルな分子たち-

    学問のすすめ(筑摩書房)  1998

Research Projects

  • Catalytic Asymmetric Dehydro-Diels-Alder Reaction for the Construction of Fused Polycyclic Heteroaromatics

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    Project Year :

    2019.04
    -
    2022.03
     

    Shibata Takanori

     View Summary

    There are several patterns of dehydro-Diels-Alder (DDA) reaction. For example, the tetradehydro-Diels-Alder (TDDA) reaction of a 1,3-enyne and alkyne gives a substituted benzene ring with perfect atom-economy. We merged two types of DDA reactions and realized the facile preparation of dibenzosilole-fused polycyclic compounds. Moreover, the benzene ring in the obtained silicon-containing cycloadduct showed high reactivity as a 1,3-diene moiety. On the other hand, we developed a Ni-catalyzed transformation initiated by non-activated C-S bond cleavage at ambient temperature along with carbothiolation to alkynes. An intramolecular reaction of diarylthioether-tethered 1,8-diyne gave sulfur-containing tetracyclic compounds. It is notable that an intermolecular reaction can also be achieved: self- and cross-coupling proceeded in complete regioselective manner. We further demonstrated the photo-catalytic activity of the obtained tetracyclic compounds in the benzylic oxidation.

  • Synthetic Strategy Using 1,3,5-Hexatriynes as a New Reagent

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

    Project Year :

    2015.04
    -
    2017.03
     

    Shibata Takanori

     View Summary

    [2+2+2] Cycloaddition is an atom-economical protocol for the synthesis of compounds possessing six-membered ring system, and many examples of cyclotrimerization of alkynes for the construction of benzene ring have been reported. On the other hand, hexaealkynylbenzenes are very useful compounds owing to their unique properties as organic electronics materials, such as liquid crystals and nonlinear optical materials. However, most of the preported protocols required multi steps along with the formation of by-products. Therefore, I developed the synthesis of hexaethynylbenzenes by [2+2+2] cycloaddition of 1,3,5-hexatriynes.

  • Chemistry of thermally stable monosubstituted thiophene S-oxide and related compounds

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    Project Year :

    2013.04
    -
    2016.03
     

    Otani Takashi, SHIBATA Takanori, MATSUO Tsukasa

     View Summary

    Thiophene S-oxide does not possess sufficient electron density for aromatization and thus readily dimerize in a [4+2] (Diels-Alder) manner. Introduction of two substituents on the thiophene ring has been required for their kinetic and/or thermodynamic stabilization for nearly a half century.
    We have succeeded in the synthesis and characterization of thermally stable monosubstituted thiophene S-oxide and S-imides stabilized by EMind (1,1,7,7-tetraethyl-3,3,5,5-tetramethyl-s-hydrindacen-4-yl) group on the 3-position. In addition to the molecular structures determined by X-ray crystallography, inversion barriers at the three-coordinated sulfur atoms have been determined by a coalescence method using diastereotopic C-3 and C-5 indacene carbon atoms as a 13C-NMR probe.

  • イリジウム錯体を用いる不活性結合の切断を伴う触媒反応の開発

    日本学術振興会  科学研究費助成事業 新学術領域研究(研究領域提案型)

    Project Year :

    2013.04
    -
    2015.03
     

    柴田 高範

     View Summary

    炭素-水素結合などの不活性結合の開裂を起点とする触媒的合成変換は、原子効率の高い理想的な手法である。本研究では、イリジウム錯体用いて、合成的に有用性の高い反応開発、特に触媒的かつエナンチオ選択的不斉反応の開発を最終目標として検討を行った。
    (1) インドールの2位のエナンチオ選択的分子内不斉アルキル化:インドールは生物活性を示す天然物に多くみられる部分構造であり、位置選択的な官能基化は重要な課題である。今回我々は3位に配向基を導入したN-アルケニルインドールを基質とした分子内不斉反応を検討した。その結果、カチオン性イリジウム錯体とキラルジホスフィン配位子から調製される遷移金属触媒を用いることで、2位のC-H結合が開裂し、引き続きアルケンと反応することで、含窒素三環性化合物が高収率かつ極めて高い不斉収率で得られた。
    (2) C-Hアルキル化による面不斉フェロセン誘導体のエナンチオ選択的合成:非対称1,2-二置換フェロセン誘導体は面不斉を有し、多くの不斉配位子のキラル骨格として利用されている。そこで我々は、配向基を用いたC-H結合開裂を起点するエナンチオ選択的反応により面不斉フェロセン化合物の合成を目標として検討を行った。種々の不斉配位子および触媒を検討した結果、天然物Carvoneから容易に合成できるCarreiraジエンが極めて有効あり、C-Hアルキル化生成物として面不斉1,2-二置換フェロセン誘導体が、高収率かつ高不斉収率で得られた。
    (3) 分子内C-Hシリル化による面不斉ベンゾシロロフェロセンのエナンチオ選択的合成:イリジウムに代え、ロジウム触媒と上記のCarreiraジエンを用いると、フェロセンのC-H結合のヒドロシランによる分子内不斉シリル化が進行する。本例は、フェロセンとベンゾシロールが縮環したベンゾシロロフェロセンの初めての、かつエナンチオ選択的合成例である。

  • Synthesis of Chiral and Cyclic pai-Conjugated System Using Cycloaddition

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    2010.04
    -
    2014.03
     

    SHIBATA Takanori

     View Summary

    We achieved an easy-to-use protocol for the synthesis of substituted o,o,o,o-tetraphenylenes: two triynes with phenylene-bridged 1,5-diyne moiety was homo-coupled by consecutive inter- and intramolecular [2+2+2] cycloadditions, and tetraphenylenes were obtained with good to excellent enantiomeric excess. We further examined meta-phenylene tethered triynes and achieved the first construction of o,m,o,m-tetraphenylenes in cis-form. In addition to the tetraphenylenes as dimers, o,m,o,m,o,m-hexaphenylenes were also obtained as trimers. In the reaction of para-phenylene tethered triynes, o,p,o,p,o,p-hexaphenylenes were major products along with the formation of o,p,o,p,o,p,o,p-octaphenylenes as tetramers.

  • 合成的活用を考慮した配向基による炭素-水素結合活性化の新展開

    日本学術振興会  科学研究費助成事業 新学術領域研究(研究領域提案型)

    Project Year :

    2011.04
    -
    2013.03
     

    柴田 高範

     View Summary

    炭素-水素結合など不活性結合の直接的な官能基化は、原子効率、工程数の削減から理想的な合成変換であるが、望みの不活性結合を位置選択的に活性化するためには、反応部位に金属触媒を接近させる「配向基」が一般に用いられる。私は、「配向基」を単なる「活性化基」として用いるのではなく、生成物の付加価値を高め、その後の多彩な合成変換を可能にする「機能性基」として位置づけ触媒反応の開発を行った。
    まず私は、カチオン性イリジウム触媒を用いることで、配向基(DG)を有するフェロセン化合物に対し、酸化的C-H結合開裂を起点とするアルキル化、アルケニル化を行った。その結果、2-pyridyl基を配向基を用いた場合、三置換、一方1-isoquinolyl基を用いた場合、二置換フェロセン化合物が選択的に得られた。
    次にカチオン性イリジウム触媒を用いたアルケン類との反応により、インドールの2位選択的なアルキル化を達成した。さらに、窒素上の置換基(Ac基とBz基)と、触媒に用いるホスフィン配位子(SEGPHOSとSDP)の適切な組み合わせにより、直鎖型(linear)と分岐型(branched)アルキル化体の選択的な合成に成功した。複素環であるインドールは多くの生理活性化合物の母骨格あり、位置選択的な炭素鎖や官能基の導入法の開発が望まれている。3位は電子豊富でありFriedel-Crafts反応に対する活性部位であるが、2位のC-H結合の直接的なアルキル化の例は、本例が初めてである。
    そして、新形式のC-H結合活性化を伴う反応として“ロールオーバー”を経る反応を目指し、3-アルキニル-2-アリールピリジンの反応を検討した。様々な遷移金属触媒の検討の結果、ロジウム触媒[Cp*RhCl2]2に触媒量の銅塩Cu(OAc)2を添加することで効率よく反応が進行し、4-アザフルオレン誘導体が得られた。

  • Catalytic Asymmetric Synthesis of Cage-type Organic Compounds by New Stereo-controlled Approach

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

    Project Year :

    2011
    -
    2012
     

    SHIBATA Takanori

     View Summary

    I reported an enantioselective ortho-lithiation of achiral paracyclophanes with oxygen atoms as directed moieties at both ends of ansa-chain using a chiral lithium reagent. The reaction of an unflippable 1,n-dioxa[n]paracyclophane (n?□11) with sec- utyllithium and (-)-sparteine gave the chiral mono-lithiated product. Additional amount of sec-butyllithium gave C_2-symmetric dilithiated product. The quenching of these lithium salts by appropriate electrophiles gave various planar-chiral aracyclophanes with excellent ee. The planar-chiral mono- and diphosphines, which were prepared by the above protocols, were used as chiral ligands in transition metal-catalyzed reactions.

  • The Origins of Chirality and Amplification in Asymmetric Autocatalysis

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)

    Project Year :

    2008
    -
    2012
     

    SOAI Kenso, KAWASAKI Tsuneomi, SHIBATA Takanori, SHINDO Hitoshi, MATSUMOTO Arimasa, TSUKIYAMA Koichi, MIYAMURA Kazuo, SAITO Yukio

     View Summary

    Biologically related compounds such as L-amino acids are composed of one of the enantiomers. The phenomenon is called biological homochirality, and the origin of homochirality has attracted broad interest. Asymmetric autocatalysis, i.e., Soai reaction, is a reaction in which chiral product acts as a chiral catalyst for its own production. It was found that chiral isotopomers of carbon, hydrogen and oxygen, spontaneous absolute asymmetric synthesis, chiral crystals formed from achiral organic compounds such as nucleic acid base act as chiral initiators of asymmetric autocatalysis. Highly enantioenriched chiral compounds withthe corresponding absolute configurations with those of chiral initiators are obtained.

  • Construction of New Chiral Skeletons Using by Catalytic Cycloaddition

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    2007
    -
    2009
     

    SHIBATA Takanori

     View Summary

    Transition metal catalyzed-reactions realize efficient and useful synthetic transformations. In particular, transition metals with chiral ligands can induce high enantioselectivity, and various types of chiral skeletons can be synthesized. I have focused on the development of chiral transition metal-catalyzed cycloadditions in this project. For example, consecutive inter- and intramolecular [2+2+2] cycloadditions of two o-phenylene-tethered triynes provided highly enantioselective synthesis of chiral substituted tetraphenylenes. The present protocol is a new and facile approach to the construction of chiral tetraphenylene skeleton. We also reported the enantioselective synthesis of the tripodal cage-type compounds with planar chirality. Intramolecular [2+2+2] cycloaddition of branched triynes, where diyne and alkyne moieties were connected by 2-aminophenol linkage, gave tripodal cyclophanes with almost perfect enantioselectivity.

  • 触媒的不斉付加環化反応を用いる新規キラル化合物群の創製と評価

    日本学術振興会  科学研究費助成事業 萌芽研究

    Project Year :

    2005
    -
    2007
     

    柴田 高範

     View Summary

    報告者は、キラルイリジウム触媒を用い、「アルキンの三量化によるベンゼン環の構築とともに軸不斉を創製する」というコンセプトで総括的に研究を行っている。今回は、複数の反応点をもつ連続反応に焦点を当て、軸不斉ビアリール骨格の構築を検討した。
    まず、1,3-ジイン部分により二つの1,6-ジイン部分が連結されたテトラインと、アルキンの分子間連続的[2+2+2]付加環化反応を検討した。その結果、従来の1,6-ジインとアルキンの反応の場合と異なり、アルキンの嵩高さがエナンチオ選択性に影響を及ぼすことがわかった。例えば2-ブチン-1,4-ジオールを嵩高いシリル基で保護したアルキンを用いることにより、90%前後の高い不斉収率で、ビアリール誘導体を得ることができた。
    次に、1,3-ジイン部分により二つのトリイン部分が連結されたヘキサインの分子内連続的[2+2+2]付加環化反応を検討した。その結果、両末端にアリール基、あるいは嵩高いイソプロピル基を導入した基質を用いることにより、対応するビアリール誘導体を高不斉収率で得た。
    さらに、ベンゼン環により架橋された1,7-ジインを出発物質として、アルキンとの分子間[2+2+2]付加環化反応、生成物の1,4-シクロヘキサジイン部分の酸化による芳香化を二回繰り返すことにより、軸不斉を有する光学活性なペンタセン骨格の合成に初めて成功した。
    これらの結果は、アルキン類の[2+2+2]付加環化反応による軸不斉の創製というコンセプトの汎用性を示すとともに、芳香環を含む多縮環型光学活性化合物の合成手法を提供したと言える。

  • Research on Asymmetric Autocatalysis, Chiral Recognition and Origin of Chirality

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Specially Promoted Research

    Project Year :

    2003
    -
    2007
     

    SOAI Kenso, KAWASAKI Tsuneomi, SATO Itaru, SHIBATA Takanori

     View Summary

    Pyrimidyl alkanol was found to act as an asymmetric autocatalysis in the reaction between pirimidine-5-carbaldehyde and diisopropylzinc, affording highly enantioenriched pyrimidyl alkanol with the same structure and absolute configuration. When asymmetric autocatalyst with very low enantiomeric excess (ee) was employed, significant amplification of ee was observed. Starting from asymmetric autocatalyst with very low ee, three consecutive asymmetric autocatalysis afforded practically enantiopure (>99.5% ee) pyrimidyl alkanol. Asymmetric autocatalysis has been employed to examine the validity of the origin of chirality. It was found that chiral inorganic crystal such as sodium chlorate act as chiral initiator of asymmetric autocatalysis. Direct irradiation of circularly polarized light (CPL) to racemic pyrimidyl alkanol and the subsequent asymmetric autocatalysis gave highly enantioenriched pyrimidyl alkanol with the related configuration to that of the direction of CPL. In addition, certain ketoolefin to which CPL induces the enantioenrichment by asymmetric photoequilibrium can act as a chiral initiator of asymmetric autocatalysis. Chiral crystals of achiral organic compound such as cytosine acts as chiral initiator of asymmetric autocatalysis. Spontaneous absolute asymmetric synthesis in the presence of achiral silica gel was achieved without adding chiral initiator in the reaction between pyrimidine-5-carbaldehyde and diisopropylzinc. Chiral discrimination of cryprochiral compound such as satirated quaternary hydrocarbon was achieved by using asymmetric autocatalysis. As described, we have found highly efficient asymmetric autocatalysis with amplification of enantioenrichment and applied the reaction to elucidate the origin of chirality and chiral discrimination.

  • Innovation of 6 Coordinate Hypervalent Compounds Bearing Carbon and Phosphorus as Central Atoms

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    Project Year :

    2005
    -
    2006
     

    AKIBA Kin-ya, SHIBATA Takanori, NAKAI Hiromi, KIKUTI Yasuaki

     View Summary

    1,6 Coordinate perphosphoranide anion (12-P-6) are usually unstable and difficult to be isolated. In order to stabilize the anion, two equivalents of the bidentate Martin ligand (hexafluorocumyl alcohol) were reacted with phosphorus trichloride to generate 4 coordinate phosphoranide anion (10-P-4) in situ. Conjugate aldehydes and 1,2-diketones were reacted with the anion (10-P-4) to effect Diels-Alder type 1,4-cycloadditon to synthesize 6 coordinate perphosphoranide anions (12-P-6). The anion (12-P-6) was isolated stable and the structure was determined by X-ray analysis when phenanhrenequinone was used as a 1,2-diketone. Gnerally, the anions (12-P-6) were hydrolyzed to give 5 cordinate phosphoranes (10-P-5) bearing ethylene aldehyde group and the aldehydes were characterixed as their 2,4-dinitrophenylhydrazones.
    2,Syntheses and structure determination by X-ray analysis of a variety of 5 coordinate hypervalent carbon species (10-C-5) were reported as full papers in the fiscal year of 2005. In 2006, we challenged to synthesize 6 coordinate hypervalent carbon species (12-C-6). Because of the new and unique idea to prepare 12-C-6 species, several attempts were tried. Finally, an allene compound which bears thioxanthene skeleton at the terminal 1,3-carbons was prepared and the two sulfur atoms were methylated to yield the 6 coordinate carbon species. For the methylation, only the strongest methylation reagent, i.e., carborane reagent, could lead to success. The reagent was developed by Professor C. Reed group of Riverside, California, USA.
    3,Syntheses, crystal and solution structures, ligand exchange and ligand coupling reactions of mixed pentaarylantimony compounds were reported as a full paper in 2007. The experiments were quite complicated and contained a variety of aspects of hypervalent pentacoordinate compounds and had been completed several years before. By analyzing the total experimental results, it was concluded that the reaction proceeded through the two apical ligands which was termed as "memory effect".

  • A New Approach to the Construction of Carbon Framework Using Metallacumulene Derivatives

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    2004
    -
    2006
     

    SHIBATA Takanori

     View Summary

    There are many reactions of 1, 2-propadienes(allenes), which have cumulated double bond moieties, as unique synthetic reagents. Among them, the features of the cumulated double bond are effectively utilized, that cannot be achieved by simple double or triple bond. In this research, I recognize vinylidene and allenylidene complexes as metal analogue of 1, 2-propadienes and 1, 2, 3-butatriene, respectively, and pay attention to the reactivity of carbon-carbon double bond in metallacumulenes. I plan to search for synthetic reactions that make the best use of their characteristics, and that use metallacumulenes as two or three carbon unit.
    I first examined the synthesis of vinylidene complexes from rhodium and iridium ones, which are known to be relatively electron-rich metals. According to the conventional methods, I tried to prepare them from low valent rhodium complexes and terminal alkynes via isomerization along with a hydrogen transfer. I failed but obtained multicyclic compounds by cycloaddition of alkyne moieties. Thus, I focused on the development of low valent late transition metal catalyzed-cycloaddition of alkynes and alkenes, especially enantioselective reaction using chiral metal catalysts.
    For example, transition metal-catalyzed[2+2+2] cycloaddition is a well-established protocol for the construction of six-membered ring systems. I developed a new type of enantioselective[2+2+2] cycloaddition for the synthesis of quaternary carbon stereocenters. The intramolecular reaction of various 1, 4-diene-ynes proceeded using a chiral rhodium catalyst and tricyclic compounds possessing a strained bicyclo[2.2.1] heptene skeleton or bicyclic cyclo-1, 3-dienes were obtained, depending on the substituent on the 1, 4-diene moiety.

  • 触媒的不斉[4+2]付加環化反応に基づく光学活性複素環化合物の合成

    日本学術振興会  科学研究費助成事業 特定領域研究

    Project Year :

    2002
    -
    2003
     

    柴田 高範

     View Summary

    報告者は、イリジウム錯体を用いる触媒的かつエナンチオ選択的[4+2]付加環化反応について検討した。その結果、置換基を持たないジエンとアルキンとの分子内反応が進行し、キラルイリジウム錯体を用いた場合には、対応するシクロヘキサ-1,4-ジエンが高不斉収率で得られことを見いだした。
    これまで数多くの報告例があるルイス酸触媒を用いる[4+2]付加環化反応(Diels-Alder反応)では、不斉場構築において、反応点近傍にあるヘテロ原子官能基へのルイス酸の配位が足がかりとなる。一方、メタラサイクルを経由する遷移金属錯体を触媒とする反応では、ヘテロ原子官能基をもたない不活性な基質間でも反応が進行するという特徴をもつ。分子内[4+2]付加環化反応は、Ni、Pd、Rh触媒などを用いる反応が知られており、カチオン性キラルRh錯体を用いる不斉反応も報告されている。しかしながら、これまで用いられている基質は、置換基を有する(主にsorbic alcohol、ヘキサ-2,4-ジエン-1-オール由来の)ジエンとアルキンあるいはアルケンとの分子内不斉反応のみであった。
    報告者は既に、[2+2+1]付加環化反応において、イリジウム錯体が有効な触媒として機能することを見いだし、不斉反応へも展開している。今回、末端ジエンとアルキンとの分子内[4+2]付加環化反応においても、イリジウム錯体が触媒として働くことを見いだした。特にキラルなジホスフィンBDPPを不斉配位子とし、溶媒として酢酸tert-ブチルを用いた場合、非カチオン性イリジウム錯体によって極めて高エナンチオ選択的に反応が進行し、対応するシクロヘキサ-1,4-ジエンが得られた。

  • 一酸化炭素の挿入を伴う触媒的アルキン-アルキンカップリング反応の開発

    日本学術振興会  科学研究費助成事業 若手研究(B)

    Project Year :

    2001
    -
    2002
     

    柴田 高範

     View Summary

    遷移金属触媒を用いる付加環化反応は、環状化合物合成において最も汎用な手法である。中でも、一酸化炭素やイソシアニドの挿入を伴う反応は、環内に合成上有用なカルボニル基、イミノ基をもつ環化生成物を与える。しかしながらこれまで、触媒的アルキン-アルキンカップリング反応によるシクロペンタジエノンの一般的な合成法はなく、また、イソシアニドの挿入を伴う反応は、基質に対し等量の遷移金属錯体を用いる例しか報告されていない。
    報告者は、イリジウム-ホスフィン錯体を用いることにより、一酸化炭素の挿入を伴う触媒的分子内アルキン-アルキンカップリング反応が進行することを見いだした。その後に他の研究者により報告されたコバルト三核カルボニル錯体を用いる高一酸化炭素圧下の触媒的アルキン-アルキンカップリングと異なり、本反応は、一酸化炭素常圧下、さらには低分圧下(0.2atm)においても効率的に進行することがわかった。また、生成物のシクロペンタジエノンは、酸処理により、容易に二重結合の異性化が進行し、さらなる合成変換が可能な二環性ジエノンが得られる。
    さらに、これまで等量のNi(O)錯体を用いる例しか知られていない、イソシアニドの挿入を伴うアルキン-アルキンカップリングについて検討した結果、ロジウム錯体を用いることにより触媒反応を達成した。本反応は、ホスフィン配位子をもたないロジウム錯体を用い、溶媒としてジブチルエーテルを選択し、かつイソシアニドを少量ずつ適切な時間間隔で添加することにより、速やかに反応が進行し、良好な収率でイミノシクロペンタジエンを与えることを見いだした。

  • 触媒的不斉カルボニル化反応による光学活性β-ラクタム類の合成

    日本学術振興会  科学研究費助成事業 特定領域研究(A)

    Project Year :

    2001
     
     
     

    柴田 高範

     View Summary

    2つの二重結合が連続した構造を持つアレンは、オレフィンやアセチレンにない特有の反応性を持ち、合成上有用な三炭素合成素子として用いられている。例えば、アリールパラジウム(II)種に対してアレン化合物を作用させると速やかに挿入反応が進行し、π-アリルパラジウム中間体を与えることが知られている。
    そこで筆者は、一酸化炭素雰囲気下、アレニルアミン化合物を用いれば、分子内のアミノ基がπ-アリルパラジウム中間体へ求核付加し、引き続き一酸化炭素の挿入を伴ってパラジウムが還元的脱離すれば、β-ラクタムが得られると考えた。実際に触媒としてPd(PPh_3)_4、塩基として炭酸カリウム用い、加熱条件によりα-アレニルアミンとヨードベンゼンの反応を行うと、予期に反してカルボニル基を環外にもつ含窒素五員環生成物が得られた。この結果は、系中で生成するフェニルパラジウム種が、アレンに挿入する前にカルボニル化され、ベンゾイルパラジウム種となり、その後アミンの求核付加により閉環したと考えられる。従って、アルゴン雰囲気下で反応を行うと、環状にフェニル基をもつ含窒素複素環であるピロール誘導体が得られた。
    反応条件を精査した結果、トルエン溶媒中、嵩高い有機塩基であるエチルジイソプロピルアミン(Hunig base)を用いた場合、反応は効率的に進行し、高収率でジヒドロピロール誘導体を与えた。本反応は、ベンゼン環上に電子吸引性基、電子供与性基いずれの置換基をもつヨー化アリールを基質として用いても進行し、対応するアリール置換複素環化合物を与えた。

  • Research on The Origin of Chrality and Asymmetric AutomultipHcation of Chiral Compounds Based on The Development of Asymmetric Autocatalysis.

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

    Project Year :

    1998
    -
    2001
     

    KENSO Soai, TAKANORI Shibata, ITARU Sato

     View Summary

    Asymmetric autocatalysis has been developed. Chiral 2-alkynyl-5-pyrimidyl alkanol was found to be a highly enantioselective asymmetric autocatalyst in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde. PracticaUy perfect asymmetric autocatalysis(>99%. >99.5% ee) is achieved. The product has been used as asymmetric autocatalyst for the next asymmetric autocatalysis. During the ten consecutive asymmetric autocatalyses, the initial pyrimidyl alkanol has automultiplied by a factor of 60 million. It was also found that the enantiomeric excess is enhanced in the asymmetric autocatalysis. When the asymmetric autocatalyst with only 0.1% ee was employed, the ee was enhanced up to >99.5% ee. In the presence of L-leucine with only 2% ee, the reaction between pyrimidine-5-carbaldehyde and diisopropylzinc afforded pyrimidyl alkanol with higher ee. This is the first example of the correlation of the chirality of circularly polarized light (CPL) with a chiral organic compound with high ee. Chiral hydrocarbon, i. e., hexahelicene, serves as a chiral initiator, and pyrimidyl alkanol with high ee was obtained. Chral inorganic crystals such as quartz and sodium chlorate work as chiral initiators. In the presence of d-quartz, (S)-pyrimidyl alkanol with 98% ee was obtained. On the other hand, in the presence of I-quartz, (R)-alkanol with 98% ee was formed. As described, we found asymmetric autocatalysis in which the ee of organic compound increases without the need for any other chiral auxiliary. Amplification from 0.1% ee to>99.5% ee has been achieved. Chiral organic compounds with low ee work as chiral initiators to afford pyrimidyl alkanol with higher ee. By using asymmetric autocatalysis, chirality of CPL is correlated with organic compound of high ee. Chiral inorganic crystals act as chiral initiators in asymmetric autocatalysis, and pyrimidyl alkanol with very high ee was formed. This is the first example of a highly enantioselective synthesis induced by chiral inorganic crystal.

  • 実用化を指向した完全不斉自己触媒系の創製

    日本学術振興会  科学研究費助成事業 奨励研究(A)

    Project Year :

    1999
    -
    2000
     

    柴田 高範

     View Summary

    報告者は、用いる不斉触媒と得られる生成物の構造ならびに絶対構造が同一である「不斉自己触媒反応」の開発を行っている。不斉触媒と生成物の構造が異なる従来の不斉反応とは異なり、不斉自己触媒系では、微量の不斉源から得られた生成物を次の反応の触媒として用いる連続反応により、触媒の劣化を考慮することなく、大量のキラル化合物が得られる。報告者は既に、ピリミジン-5-カルバルデヒドのジアルキル亜鉛による不斉イソプロピル化反応においてほぼ定量的(>99%)、かつほぼ完全にエナンチオ選択的(>99.5%e.e.)に進行する完全不斉自己触媒反応系を見いだした。さらに、最初に用いる不斉自己触媒として極めて低鏡像体過剰率のピリミジルアルカノールを用いても、連続反応によりほぼ一方の鏡像体のみが得られることを報告した。
    今回、上記不斉自己触媒系の応用、実用化を目指し、始めに添加するキラル化合物として、不斉自己触媒であるピリミジルアルカノールではなく、それ以外の構造の異なる化合物をキラル開始剤として用いて同条件下反応を試みた。その結果、極めて低鏡像体過剰率(0.1%e.e.以下)のアルコール、アミン、カルボン酸などがキラル開始剤として作用し、高い鏡像体過剰率のピリミジルアルカノールが生成した。得られるピリミジルアルカノールが、その鏡像体過剰率を保ったまま、α-ヒドロキシカルボン酸あるいはα-アミノ酸誘導体へと変換できることを見いだしたことから、本結果は、種々の低鏡像体過剰率の有機化合物が、有用なキラルプールの供給源となりうることを意味している。

  • 自己完結型不斉環元反応の開発

    日本学術振興会  科学研究費助成事業 奨励研究(A)

    Project Year :

    1997
    -
    1998
     

    柴田 高範

     View Summary

    私は用いる不斉配位子と得られる生成物の構造、ならびに絶対配置が同一である自己完結型不斉反応の開発を行った。従来型不斉反応、すなわち用いる不斉配位子と生成物とが全く異なる構造を有する不斉反応と比べ、自己完結型不斉反応は、1)反応後両者を分離精製する必要がない、2)得られた生成物を次の反応で不斉配位子として用いる連続反応が可能である、などの利点を持つ。
    平成9、10年度の研究により、上記自己完結型不斉反応をα-アミノケトンの不斉還元反応において実現した。すなわち、不斉配位子としてβ-アミノアルコール、還元剤として水素化アルミニウムリチウム、補助配位子としてN-エチルアニリンを用い、対応するα-アミノケトンの不斉還元反応を行ったところ、用いた不斉配位子と同一な構造、絶対配置を有するβ-アミノアルコールが高不斉収率で得られた。
    さらに平成10年度において、触媒的自己完結型不斉還元反応の開発を目指し研究を進めた。従来型触媒的不斉還元反応として、基質に対し触媒量の不斉配位子を用いるケトン、あるいはケトイミンのボラン還元反応が知られている。そこで予備的実験として等量のアミノアルコールを不斉配位子として対応するα-アミノケトン、ケトイミンの自己完結型不斉還元反応をボラン錯体を還元剤として用い行った。その結果、ボラン還元反応においても自己完結型不斉還元反応は達成されるが、上記したアルミニウムヒドリドを用いる場合と比べ一般に不斉収率が低い結果を与えた。例えば、窒素上に嵩高い2級アルキル基であるジフェニルメチル基を持つアミノアルコールを不斉配位子とするケトイミンの不斉還元反応で、不斉配位子と同一の絶対配置を持つアミノアルコールが得られたが、その不斉収率は最高11%e.e.であり、さらなる検討を要するを言える。

  • 不斉還元におけるキラル分子の自己増殖

    日本学術振興会  科学研究費助成事業 重点領域研究

    Project Year :

    1997
     
     
     

    そ合 憲三, 柴田 高範

     View Summary

    従来の不斉合成反応では、不斉配位子と生成物の構造は異なり、異型の不斉配位子および、反応後の不斉配位子と生成物との分離操作が必要であった。これに対し、本研究では不斉配位子と生成物の構造が同一で、異型不斉配位子が不要かつ不斉配位子と生成物との分離操作が不要である省エネ・省資源型の不斉自己増殖反応の開発および関連する不斉合成法の開拓を目的とする。
    キラルなβ-アミノアルコールを不斉配位子とする水素化アルミニウムリチウムによるα-アミノケトンの不斉還元により、β-アミノアルコールである不斉配位子が最高90%e.e.で不斉自己増殖することを世界で最初に見出した。すなわち、光学的にほぼ純粋な(S)-フェニル-2-ピロリジニルエタノールを不斉配位子に用い、N-エチルアニリン存在下で水素化アルミニウムリチウムとキラルな錯体を形成させ、2-ピロリジニルアセトフェノンを不斉還元したところ、不斉配位子と同一構造同一絶対配置の(S)-フェニル-2-ピロリジニルエタノールが収率82%、不斉収率90%e.e.で得られた。さらに、ピペリジンあるいはモルフォリン骨格を有するアミノアルコールを不斉配位子に用いた場合も、不斉還元において78-84%e.e.で自己増殖することを明らかにした。以上のように異型の不斉源が不要、かつ不斉配位子と生成物とが同一であるのでこれらの分離が不要である次世代の不斉合成反応を開発した。
    また、新規の不斉配位子の開発として、キラルなデンドリマ-およびアミノアルコールを不斉配位子とするN-Dppイミンのジアルキル亜鉛による不斉アルキル化反応により、対応するDppアミンが良好ないし高いエナンチオ選択性で得られた。

  • 1,3,5-ヘキサトリインの特異な反応性を駆使した新規合成法の開発

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(挑戦的萌芽研究)

  • 不斉自己増殖反応の一般化ならびに機構の解明

    科学研究費助成事業(東京理科大学)  科学研究費助成事業(奨励研究(A))

  • 不斉還元におけるキラル分子の自己増殖

    科学研究費助成事業(東京理科大学)  科学研究費助成事業(重点領域研究)

  • 自己完結型不斉環元反応の開発

    科学研究費助成事業(東京理科大学)  科学研究費助成事業(奨励研究(A))

  • Research on The Origin of Chrality and Asymmetric AutomultipHcation of Chiral Compounds Based on The Development of Asymmetric Autocatalysis.

  • 実用化を指向した完全不斉自己触媒系の創製

    科学研究費助成事業(岡山大学)  科学研究費助成事業(奨励研究(A))

  • 触媒的不斉カルボニル化反応による光学活性β-ラクタム類の合成

    科学研究費助成事業(岡山大学)  科学研究費助成事業(特定領域研究(A))

  • 一酸化炭素の挿入を伴う触媒的アルキン-アルキンカップリング反応の開発

    科学研究費助成事業(岡山大学)  科学研究費助成事業(奨励研究(A))

  • 触媒的不斉[4+2]付加環化反応に基づく光学活性複素環化合物の合成

    科学研究費助成事業(岡山大学)  科学研究費助成事業(特定領域研究)

  • Research on Asymmetric Autocatalysis, Chiral Recognition and Origin of Chirality

  • A New Approach to the Construction of Carbon Framework Using Metallacumulene Derivatives

  • 触媒的不斉付加環化反応を用いる新規キラル化合物群の創製と評価

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(萌芽研究)

  • Innovation of 6 Coordinate Hypervalent Compounds Bearing Carbon and Phosphorus as Central Atoms

  • Construction of New Chiral Skeletons Using by Catalytic Cycloaddition

  • The Origins of Chirality and Amplification in Asymmetric Autocatalysis

  • Synthesis of Chiral and Cyclic pai-Conjugated System Using Cycloaddition

  • 合成的活用を考慮した配向基による炭素-水素結合活性化の新展開

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(新学術領域研究(研究領域提案型))

  • Catalytic Asymmetric Synthesis of Cage-type Organic Compounds by New Stereo-controlled Approach

  • イリジウム錯体を用いる不活性結合の切断を伴う触媒反応の開発

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(新学術領域研究(研究領域提案型))

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Misc

  • Highly Enantioselective Synthesis of Axially Chiral PAH Compounds via C-C Bond Activation of Biphenylenes and Their Physical Properties

    塩澤夏海, 高野秀明, 今井喜胤, KANYIVA Kyalo Stephen, 柴田高範

    日本化学会春季年会講演予稿集(CD-ROM)   100th  2020

    J-GLOBAL

  • 8-exo-dig-Selective Cycloisomerization for the Synthesis of Dibenzo[b,e][1,4]diazocines Using Cationic AuICatalysts

    Mamoru Ito, Daisuke Inoue, Asahi Takaki, Kyalo Stephen Kanyiva, Takanori Shibata

    European Journal of Organic Chemistry   2018   4740 - 4747  2018.09

     View Summary

    © 2018 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim The cationic AuI-catalyzed intramolecular reaction of N-propargyl-2-anilinoanilines gave a diazocine skeleton via 8-exo-dig-selective cycloisomerization by the suppression of 6-endo-dig cycloisomerization. Both terminal and internal alkynes could be used according to the choice of ligand of the AuIcomplex, and various dibenzo[b,e][1,4]diazocines were obtained. Control experiments suggested that two nitrogen atoms in the tether of substrates were critical in this selective transformation.

    DOI

  • Ir-Catalyzed Enantioselective Intra- and Intermolecular Formal C−H Conjugate Addition to β-Substituted α,β-Unsaturated Esters

    Takanori Shibata, Hisaki Kurita, Sahoko Onoda, Kyalo Stephen Kanyiva

    Asian Journal of Organic Chemistry   7   1411 - 1418  2018.07

     View Summary

    © 2018 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinheim An enantioselective intramolecular formal C−H conjugate addition of 4-methyl 1-aryl 2-methylfumarates proceeded using a chiral iridium catalyst. A benzoylamide group served as a directing group, and chiral γ-lactones with a quaternary all-carbon stereogenic center were obtained with up to excellent ee. In the intermolecular reaction of N-arylbenzamides with β-substituted acrylates, C−H bond activation selectively occurred at the ortho-position of carbonyl groups, and highly enantioselective formal C−H conjugate addition proceeded.

    DOI

  • Ir-catalyzed synthesis of substituted tribenzosilepins by dehydrogenative C-H/Si-H coupling

    Takanori Shibata, Ninna Uno, Tomoya Sasaki, Hideaki Takano, Tatsuki Sato, Kyalo Stephen Kanyiva

    Journal of Organic Chemistry   83 ( 7 ) 3426 - 3432  2018.04

     View Summary

    The Ir-catalyzed intramolecular reaction of 2′,6′-diaryl-2-(hydrosilyl)biphenyls gave substituted tribenzosilepins by direct dehydrogenative C-H/Si-H coupling. This is the first example of catalytic construction of the tribenzosilepin skeleton. Enantiomerically pure tribenzosilepin was prepared by optical resolution using chiral HPLC, and its inversion barrier was calculated by measurement of rate of racemization using the Eyring kinetic equation under heating conditions.

    DOI

  • Catalytic Dearomative Spirocyclization via Gold Carbene Species Derived from Ynamides: Efficient Synthesis of 2-Azaspiro[4.5]decan-3-ones

    Mamoru Ito, Ryosuke Kawasaki, Kyalo Stephen Kanyiva, Takanori Shibata

    Chemistry - A European Journal   24 ( 15 ) 3721 - 3724  2018.03

     View Summary

    An intramolecular catalytic dearomatization of phenols via gold carbene species proceeded to provide 2-azaspiro[4.5]decan-3-ones. The use of NHC ligand and water as a co-solvent was critical for achieving high reactivity. This reaction did not require hazardous diazo compounds as carbene sources and proceeded even under air. The obtained spirocyclic product could be readily transformed into a gabapentin derivative by hydrogenation and deprotection.

    DOI

  • Silver-Catalyzed Efficient Synthesis of Oxindoles and Pyrroloindolines via α-Aminoalkylation of N-Arylacrylamides with Amino Acid Derivatives

    Kyalo Stephen Kanyiva, Sohei Makino, Takanori Shibata

    Chemistry - An Asian Journal   13 ( 5 ) 496 - 499  2018.03

     View Summary

    α-Aminoalkylation of N-arylacrylamides with amino acid derivatives was achieved by silver-catalysis in moderate to high yields. The reaction provides an efficient strategy for the synthesis of functionalized oxindoles, and is suitable for a wide range of N-arylacrylamides and amino acids, both of which are inexpensive and readily available. The oxindoles obtained were readily transformed into densely functionalized pyrroloindolines by deprotection and cyclization in one pot.

    DOI

  • Metal-Free N–H/C–H Coupling for Efficient Asymmetric Synthesis of Chiral Dihydroquinoxalinones from Readily Available α-Amino Acids

    Kyalo Stephen Kanyiva, Masashi Horiuchi, Takanori Shibata

    European Journal of Organic Chemistry   2018 ( 8 ) 1067 - 1070  2018.02

     View Summary

    We have developed a method for the synthesis of dihydroquinoxalinones via intramolecular N–H/C–H coupling using hypervalent iodine. The starting materials were prepared from inexpensive and readily available aniline and amino acid derivatives. Various functional groups were tolerated to give multisubstituted dihydroquinoxalinones in moderate to excellent yields. The chirality of the amino acid was transferred to the desired target compound without a loss of enantiomeric excess. Preliminary mechanistic studies indicated that the reaction proceeds via an ionic mechanism.

    DOI

  • Enantioselective Synthesis of Sulfur-Containing Medium-Ring Heterocycles with Axial Chiralities by Catalytic Intramolecular [2+2+2] Cycloaddition

    Akihito Mitake, Toru Fusamae, Kyalo Stephen Kanyiva, Takanori Shibata

    European Journal of Organic Chemistry   2017 ( 48 ) 7266 - 7270  2017.12

     View Summary

    The rhodium-catalyzed enantioselective intramolecular cycloaddition of triynes connected by sulfur-containing tethers gave tribenzothiepins and a tribenzodithiocin in high yields with good-to-excellent enantiomeric excesses. The present protocol generated axial chiralities fused with medium-ring heterocycles. In particular, this is the first example of the catalytic and highly enantioselective construction of a tribenzodiheterocin skeleton.

    DOI

  • Sulfur-directed carbon-sulfur bond cleavage for Rh-catalyzed regioselective alkynylthiolation of alkynes

    Takanori Shibata, Akihito Mitake, Yosuke Akiyama, Kyalo Stephen Kanyiva

    CHEMICAL COMMUNICATIONS   53 ( 64 ) 9016 - 9019  2017.08

     View Summary

    Sulfur-directed sp C-S bond cleavage along with a regioselective reaction with alkynes proceeded to give (Z)-enyne sulfides in high to excellent yields. Mechanistic studies were conducted, including characterization of an intermediate. An intramolecular variant realized the construction of a dibenzodithiepin skeleton, which is a seven-membered ring with two sulfur atoms.

    DOI

  • Thermally Stable Monosubstituted Thiophene 1-Oxide and 1-Imides Stabilized by a Bulky Rind Group at Their 3-Position: Synthesis, Structure, and Inversion Barriers on the Sulfur Atom

    Takashi Otani, Mayu Miyoshi, Takanori Shibata, Tsukasa Matsuo, Daisuke Hashizume, Kohei Tamao

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   90 ( 6 ) 697 - 705  2017.06

     View Summary

    The synthesis and characterization of thermally stable monosubstituted thiophene 1-oxide and 1-imides stabilized by EMind (1,1,7,7-tetraethyl-3,3,5,5-tetramethyl-s-hydrindacen-4yl) group on the 3-position are described. In addition to the molecular structures determined by X-ray crystallography, inversion barriers at the three-coordinated sulfur atoms have been determined by a coalescence method using diastereotopic C-3 and C-5 indacene carbon atoms as a (CNMR)-C-13 probe.

    DOI

  • Intramolecular C-H Alkenylation of N-Alkynylindoles: Exo and Endo Selective Cyclization According to the Choice of Metal Catalyst

    Takanori Shibata, Takumi Baba, Hideaki Takano, Kyalo Stephen Kanyiva

    ADVANCED SYNTHESIS & CATALYSIS   359 ( 11 ) 1849 - 1853  2017.06

     View Summary

    The intramolecular reaction of 3-acetyl-N-alkynylindoles proceeded via C-H bond cleavage at the C2 position. Iridium and rhodium catalysts selectively promoted 6-exo-dig and 7-endo-dig cyclization, respectively, and N-fused tricyclic compounds were obtained.

    DOI

  • Facile Two-Step Synthesis of 1,10-Phenanthroline-Derived Polyaza[7]helicenes with High Fluorescence and CPL Efficiency

    Takashi Otani, Ami Tsuyuki, Taiki Iwachi, Satoshi Someya, Kotaro Tateno, Hidetoshi Kawai, Takao Saito, Kyalo Stephen Kanyiva, Takanori Shibata

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   56 ( 14 ) 3906 - 3910  2017.03

     View Summary

    A facile two-step synthesis of aza[7]helicenes possessing a 6-5-6-6-6-5-6 skeleton from commercially available 2,9-dichloro-1,10-phenanthroline via double amination with aniline derivatives followed by hypervalent iodine reagent-mediated intramolecular double-NH/CH couplings was developed. Single-crystal X-ray analyses of the helicenes revealed unique structures, including both a significantly twisted center and planar terminals of the skeleton. The azahelicenes show high fluorescent quantum yields (Fs) under both neutral (Phi: 0.25-0.55) and acidic conditions (Phi: up to 0.80). An enantiomerically pure aza[7] helicene showed high circularly polarized luminescence (CPL) activity under both neutral and acidic conditions (g(lum): up to 0.009).

    DOI

  • Cationic Au(I)-catalyzed cycloisomerization of N-(2-alkynylphenyl)indolines for the construction of indolobenzazepine skeleton

    Mamoru Ito, Daisuke Inoue, Ryosuke Kawasaki, Kyalo Stephen Kanyiva, Takanori Shibata

    Heterocycles   94 ( 12 ) 2229 - 2246  2017

     View Summary

    An intramolecular reaction of N-(2-alkynylphenyl)indolines proceeded efficiently to give indolo[1,7-ab][1]benzazepine derivatives in high to excellent yields by cationic Au(I)-catalyzed 7-endo-dig selective cycloisomerization along with DDQ oxidation. The present transformation could be used for the intramolecular reaction of N-(2-alkynylphenyl)-1,2,3,4-tetrahydroquinoline and N-(2-alkynylphenyl)-N-methylaniline, and construction of a dibenzazepine skeleton was achieved.

    DOI

  • Enantioselective Formal C-H Conjugate Addition of Acetanilides to beta-Substituted Acrylates by Chiral Iridium Catalysts

    Takanori Shibata, Masamichi Michino, Hisaki Kurita, Yu-ki Tahara, Kyalo Stephen Kanyiva

    CHEMISTRY-A EUROPEAN JOURNAL   23 ( 1 ) 88 - 91  2017.01

     View Summary

    The Ir-catalyzed enantioselective reaction of substituted acetanilides with beta-substituted alpha,beta-unsaturated esters provided chiral 3,3-disubstituted propanoates in high yield with good-to-excellent enantiomeric excess (up to 99% ee). This transformation, initiated by sp(2) C-H bond activation, is the first example of enantioselective formal C-H conjugate addition to beta-substituted alpha,beta-unsaturated carbonyl compounds. The starting materials are commercially available and/or readily accessible.

    DOI

  • Point-to-Point Ultra-Remote Asymmetric Control with Flexible Linker

    Tsuneomi Kawasaki, Yasuyuki Ishikawa, Yoshihiro Minato, Takashi Otsuka, Shigeru Yonekubo, Itaru Sato, Takanori Shibata, Arimasa Matsumoto, Kenso Soai

    CHEMISTRY-A EUROPEAN JOURNAL   23 ( 2 ) 282 - 285  2017.01

     View Summary

    An ultra-remote intramolecular (point-to-point) asymmetric control through 38 bonds (1,39-asymmetric induction) has been achieved by using the principle of direct supramolecular orientation of catalytic and reactive moieties in asymmetric autocatalysis. We found the highly stereoselective diisopropylzinc addition reaction using designed molecules possessing pyrimidine sites at each terminal of a conformationally flexible simple methylene chain.

    DOI

  • Construction of a Polycyclic Conjugated System Containing a Dibenzazepine Moiety by Cationic Gold(I)-Catalyzed Cycloisomerization

    Mamoru Ito, Ryosuke Kawasaki, Kyalo Stephen Kanyiva, Takanori Shibata

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY   2016 ( 31 ) 5234 - 5237  2016.11

     View Summary

    A new pi-conjugated system of nitrogen-containing polycyclic compounds was constructed by cationic Au-I-catalyzed cycloisomerization. Intramolecular reaction of 9-(2-alkynylphenyl)-9H-carbazole derivatives gave a variety of penta- and hexacyclic compounds possessing a dibenzazepine skeleton. The rigid carbazole structure was responsible for efficient 7-endo-dig cycloisomerization.

    DOI

  • Enantioselective synthesis of planar-chiral 1,11-dioxa-[11]paracyclophane-derived phosphoramidites and their use as chiral ligands

    Madhurima Hazra, Kyalo Stephen Kanyiva, Takanori Shibata

    TETRAHEDRON-ASYMMETRY   27 ( 20-21 ) 1081 - 1087  2016.11

     View Summary

    A library of bench-stable planar-chiral 1,11-dioxa[11]paracyclophane-derived phosphoramidites was synthesized by a three step procedure: enantioselective ortho-lithiation, reductive amination and coupling with phosphorochloridites. The efficacy of these phosphoramidite as chiral ligands was tested in the Pd-catalyzed allylic alkylation of dimethyl malonate and the Cu-catalyzed ethylation of chalcone under the reported conditions, with moderate enantioselectivity being obtained. (C) 2016 Elsevier Ltd. All rights reserved.

    DOI

  • Pt-Catalyzed Enantioselective Cycloisomerization for the Synthesis of Planar-Chiral Ferrocene Derivatives

    Takanori Shibata, Ninna Uno, Tomoya Sasaki, Kyalo Stephen Kanyiva

    JOURNAL OF ORGANIC CHEMISTRY   81 ( 15 ) 6266 - 6272  2016.08

     View Summary

    Enantioselective cycloisomerization of 2-ethynyl-1-ferrocenylbenzene derivatives proceeded by using a chiral cationic platinum catalyst at room temperature. The intramolecular reaction gave planar-chiral naphthalene-and anthracene-fused ferrocene derivatives with high to excellent ee.

    DOI

  • Enantioselective Synthesis of Planar-Chiral 1,n-Dioxa[n]paracyclophane-Based Phosphites and Their Application as Chiral Ligands

    Takanori Shibata, Miku Fukai, Ryosuke Sekine, Madhurima Hazra, Kyalo Stephen Kanyiva

    SYNTHESIS-STUTTGART   48 ( 16 ) 2664 - 2670  2016.08

     View Summary

    Various planar-chiral 1,n-dioxa[n]paracyclophanes possessing a phenolic hydroxyl group have been synthesized via enantioselective ortho-lithiation. Subsequent reaction with 2,2-biarylene phosphorochloridites gave a new family of chiral phosphites. These phosphites were then used as chiral ligands in the enantioselective palladium-catalyzed allylic alkylation of dimethyl malonate with (E)-1,3-diphenylallyl acetate and the rhodium-catalyzed 1,4-addition of phenylboronic acid to cyclohex-2-enone.

    DOI

  • Raman study on pentacene:C-60 bulk heterojunction films

    Yasuhiro Iwasawa, Tomoya Sasaki, Takanori Shibata, Yukio Furukawa

    VIBRATIONAL SPECTROSCOPY   84   133 - 138  2016.05

     View Summary

    We measured 785 nm excited Raman and infrared spectra of pentacene-d(14). The observed spectra were assigned on the basis of the Raman and infrared spectra calculated by the density functional theory (DFT) method at the B3LYP/6-311 + G** level. We measured 785 nm excited Raman spectrum of a pentacne-d(14): C-60 bulk heterojunction film. The spectrum was assigned on the basis of the wavenumber shifts upon deuteration of pentacene. The assignments of the 1462 and 493 cm(-1) A(g) bands of C-60 were confirmed. The 511, 453, and 256 cm(-1) bands, which were observed only in pentacene:C-60 bulk heterojunction films, did not show large deuteration shifts. This result indicates that the 511, 453, and 256 cm(-1) bands are attributed to activation of the silent modes of C-60 due to symmetry lowering. (C) 2016 Elsevier B.V. All rights reserved.

    DOI

  • Strategies for the Total Synthesis of Clavicipitic Acid

    Mamoru Ito, Yu-ki Tahara, Takanori Shibata

    CHEMISTRY-A EUROPEAN JOURNAL   22 ( 16 ) 5468 - 5477  2016.04

    Book review, literature introduction, etc.  

     View Summary

    Clavicipitic acid is an ergot alkaloid, which was isolated from Claviceps strain and Claviceps fusiformis. Its unique tricyclic azepinoindole skeleton has attracted synthetic chemists, and various strategies have been developed for its total synthesis. These strategies can be generally categorized into two types based on the synthetic intermediates, namely, 4-substituted gramine derivatives and 4-substituted tryptophan derivatives. This Minireview summarizes the reported total syntheses from the point of these two key intermediates

    DOI PubMed

  • Iridium-Catalyzed Formal [4+1] Cycloaddition of Biphenylenes with Alkenes Initiated by C-C Bond Cleavage for the Synthesis of 9,9-Disubstituted Fluorenes

    Hideaki Takano, Kyalo Stephen Kanyiva, Takanori Shibata

    ORGANIC LETTERS   18 ( 8 ) 1860 - 1863  2016.04

     View Summary

    An Ir-catalyzed intermolecular reaction of biphenylenes as a C4 unit with various alkenes as a Cl unit gave 9,9-disubstituted fluorenes in moderate to high yields. Preliminary mechanistic studies revealed that this formal [4 + I] cycloaddition probably proceeds via C-C bond cleavage, alkene insertion, beta-hydrogen elimination, intramolecular alkene insertion, and then reductive elimination. An example of enantioselective reaction was also disclosed.

    DOI

  • Enantioselective Synthesis of Aminoindan Carboxylic Acid Derivatives by the Catalytic Intramolecular [2+2+2] Cycloaddition of Amino-Acid-Tethered Triynes

    Yu-ki Tahara, Shuhei Obinata, Kyalo Stephen Kanyiva, Takanori Shibata, Attila Mandi, Tohru Taniguchi, Kenji Monde

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY   2016 ( 7 ) 1405 - 1413  2016.03

     View Summary

    The enantioselective synthesis of aminoindan carboxylic acid (Aic) derivatives was achieved by Rh-catalyzed intramolecular [2+2+2] cycloaddition of amino-acid-tethered triynes. This reaction, along with recrystallization, gave chiral tethered Aic derivatives with excellent enantiomeric excess. Subsequent hydrolysis of the tethered Aic compounds afforded chiral Aic derivatives, which were further transformed into a free Aic and its dimethyl ester in good yields.

    DOI

  • Catalytic and Enantioselective Synthesis of Chiral Multisubstituted Tribenzothiepins by Intermolecular Cycloadditions

    Yu-ki Tahara, Riku Matsubara, Akihito Mitake, Tatsuki Sato, Kyalo Stephen Kanyiva, Takanori Shibata

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   55 ( 14 ) 4552 - 4556  2016.03

     View Summary

    The first catalytic and highly enantioselective synthesis of tribenzothiepin derivatives was achieved. Two types of intermolecular cycloadditions using either diphenyl-sulfide-tethered diynes or 2-phenyl sulfanylbenzene-tethered diynes with a monoalkyne successfully gave chiral multisubstituted tribenzothiepins in good to excellent eevalues under mild conditions. The inversion energy of this saddle-shaped molecule was calculated by measurement of the racemization rate of chiral tribenzothiepins using the Eyring kinetic equation under heating conditions. The present protocol could also be used to prepare a chiral tribenzoselenepin.

    DOI

  • Multi-substituted dibenzophosphole oxide synthesis by the catalytic [2+2+2] cycloaddition of phosphorylbenzene- tethered diynes with various alkynes

    Yu-Ki Tahara, Tatsuki Sato, Riku Matsubara, Kyalo Stephen Kanyiva, Takanori Shibata

    Heterocycles   93 ( 2 ) 685 - 704  2016

     View Summary

    Rhodium-catalyzed intermolecular [2+2+2] cycloaddition of phosphorylbenzene-tethered 1, 6-diynes with alkynes gave dibenzophosphole oxide derivatives. Various monoalkynes were applicable in this reaction as coupling partners, and dibenzophosphole oxide derivatives substituted with aromatic ring(s) including dibenzothiophene(s) were obtained. The asymmetric desymmetrization of a prochiral phosphorylbenzene-tethered triyne gave a chiral dibenzophosphole oxide derivative with high ee.

    DOI

  • Total Synthesis of cis-Clavicipitic Acid from Asparagine via Ir-Catalyzed CH bond Activation as a Key Step

    Yu-ki Tahara, Mamoru Ito, Kyalo Stephen Kanyiva, Takanori Shibata

    CHEMISTRY-A EUROPEAN JOURNAL   21 ( 32 ) 11340 - 11343  2015.08

     View Summary

    4-Substituted tryptophan derivatives and the total synthesis of cis-clavicipitic acid were achieved in reactions in which Ir-catalyzed CH bond activation was a key step. The starting material for these reactions is asparagine, which is a cheap natural amino acid. The reductive amination step from the 4-substituted tryptophan derivative gave cis-clavicipitic acid with perfect diastereoselectivity.

    DOI PubMed

  • Cationic iridium-catalyzed C-H alkylation of 2-substituted pyridine N-oxides with acrylates

    Takanori Shibata, Hideaki Takano

    Organic Chemistry Frontiers   2 ( 4 ) 383 - 387  2015.04

     View Summary

    The reaction of 2-arylmethyl-, 2-aryl-, and 2-alkyl substituted pyridine N-oxides with acrylates proceeded in the presence of a cationic Ir-rac-BINAP catalyst under heating conditions. Various 2,6-disubstituted pyridine N-oxides were obtained by C-H alkylation at the C6-position.

    DOI

  • Iridium-Catalyzed Intramolecular Enantioselective C-H Alkylation at the C-2 Position of N-Alkenylindoles

    Takanori Shibata, Naoto Ryu, Hideaki Takano

    ADVANCED SYNTHESIS & CATALYSIS   357 ( 6 ) 1131 - 1135  2015.04

     View Summary

    Intramolecular enantioselective alkylation of N-alkenylindoles proceeded via C-H bond cleavage at the C-2 position in the presence of a cationic iridium catalyst with a diphosphine ligand. Aroyl groups at the C-3 position of the indoles operated as effective directing groups, and chiral 1-substituted-2,3-dihydro-1H-pyrrolo[1,2-a] indoles were obtained in high yield with excellent ee.

    DOI

  • [2+2+2] CYCLOADDITION OF SULFANYLBENZENE-TETHERED DIYNES WITH ALKYNES FOR THE SYNTHESIS OF MULTI-SUBSTITUTED DIBENZOTHIOPHENE DERIVATIVES

    Yu-Ki Tahara, Riku Matsubara, Takanori Shibata

    HETEROCYCLES   90 ( 2 ) 1094 - 1110  2015.01

     View Summary

    An intermolecular [2+2+2] cycloaddition of sulfanyl- and sulfonylbenzene-tethered 1,6-diynes with alkynes using rhodium catalysts gave dibenzothiophene derivatives in moderate to excellent yields. The consecutive reaction of tetraynes with an alkyne gave an axially chiral 1,1'-bi(dibenzothiophenyl) and its tetraoxide with up to excellent ee.

    DOI

  • Enantioselective sp(3) C-H alkylation of gamma-butyrolactam by a chiral Ir(I) catalyst for the synthesis of 4-substituted gamma-amino acids

    Yu-ki Tahara, Masamichi Michino, Mamoru Ito, Kyalo Stephen Kanyiva, Takanori Shibata

    CHEMICAL COMMUNICATIONS   51 ( 93 ) 16660 - 16663  2015

     View Summary

    Ir-catalyzed sp(3) C-H alkylation of gamma-butyrolactam with alkenes was used for the highly enantioselective synthesis of 5-substituted gamma-lactams, which were readily converted into chiral 4-substituted gamma-amino acids. A broad scope of alkenes was amenable as coupling partners, and the alkylated product using acrylate could be transformed into the key intermediate of pyrrolam A synthesis.

    DOI PubMed

  • Evaluation of strength of soft ground improved by vacuum consolidation

    T. Shibata, S. Nishimura, M. Fujii, A. Murakami

    Geotechnical Engineering   46   95 - 102  2015.01

     View Summary

    This paper presents the numerical evaluation of the strength and stability of a ground improved via vacuum consolidation combined with a preloading embankment. To assess the stability of soft grounds, the undrained shear strength is definitely required. A numerical analysis is desirable for predicting the strength of the improved ground, and the elasto-plastic FEM for soil-water coupled problems, incorporating the SYS Cam-clay model, is adopted in two dimensions. The compression index of clay and the coefficient of permeability of organic soil, which are the primary factors for evaluating the ground behavior, are identified through an inverse analysis from the measured settlements. As the inverse approach, the particle filter is employed to account for the strong nonlinearity of the ground behavior. A stability analysis of the slip surface method is performed based on the evaluated undrained shear strength to assess the effect of the ground improvement on the construction of earth structures. The results show the validity of the ground improvement using vacuum consolidation with a preloading embankment.

  • Asymmetric synthesis of multi-substituted triptycenes via enantioselective alkynylation of 1,5-dibromoanthracene-9,10-dione

    Takanori Shibata, Yuri Kamimura

    TETRAHEDRON-ASYMMETRY   26 ( 1 ) 41 - 45  2015.01

     View Summary

    Enantioselective alkynylation of 1,5-dibromoanthracene-9,10-dione by alkynyllithium reagents prepared from alkynes, n-BuLi, and sparteine gave chiral cis-diols possessing two alkyne moieties with moderate ee. Subsequent Ru-catalyzed [2+2+2] cycloaddition of the diol with alkynes afforded chiral 1,5-dibromotriptycenes. (C) 2014 Elsevier Ltd. All rights reserved.

    DOI

  • Enantioselective synthesis of planar-chiral benzosiloloferrocenes by Rh-catalyzed intramolecular C-H silylation

    Takanori Shibata, Tsubasa Shizuno, Tomoya Sasaki

    CHEMICAL COMMUNICATIONS   51 ( 37 ) 7802 - 7804  2015

     View Summary

    The first synthesis of planar-chiral benzosiloloferrocenes was achieved by the intramolecular reaction of 2-(dimethylhydrosilyl)-arylferrocenes. The enantioselective cross dehydrogenative coupling of an sp(2) C-H bond of ferrocene with a Si-H bond proceeded efficiently with the use of a Rh-chiral diene catalyst.

    DOI

  • Synthesis of Multicyclic Heterocycles Initiated by C-H Bond Activation Along with "Rollover" Using a Rh(III) Catalyst

    Takanori Shibata, Satoshi Takayasu

    HETEROATOM CHEMISTRY   25 ( 5 ) 379 - 388  2014.11

     View Summary

    Various multicyclic heterocycles were synthesized via rollover as the key pathway using a Rh(III) catalyst with a catalytic amount of sodium pivalate or copper(II) acetate. 3-Alkynyl-2-heteroarylpyridines were transformed into tri- or tetracyclic heterocycles containing two heteroatoms via an intramolecular alkyne insertion. 3-Aryloyl-2-arylpyridines were derived into 4-azafluoren-9-ols via the intramolecular carbonyl insertion.

    DOI

  • Synthesis of macrocyclic heteroarylenes by consecutive inter- and intramolecular cycloadditions of thiophenylene-tethered triynes

    Takanori Shibata, Masako Fujimoto, Takashi Otani

    TETRAHEDRON   70 ( 45 ) 8453 - 8461  2014.11

     View Summary

    Consecutive inter- and intramolecular [2+2+2] cycloadditions of various thiophenylene-tethered triynes were comprehensively studied by using chiral Rh catalysts. When we started from 2,3- and 3,4-thiophenylene-tethered substrates, dimerization proceeded and chiral tetraheteroarylenes were obtained. In contrast, reactions of 2,5-thiophenylene-tethered substrates gave hexaheteroarylenes as trimers. When bis- and tris(2,5-thiophenylene)-tethered triynes were used, mixtures of dimers and trimers were obtained, which included macrocyclic systems that contained up to 12 aromatic rings, and their photophysical properties were measured. (C) 2014 Elsevier Ltd. All rights reserved.

    DOI

  • Catalytic [2+2+2] Cycloaddition of Benzothiophene Dioxides with alpha,omega-Diynes for the Synthesis of Condensed Polycyclic Compounds

    Yu-ki Tahara, Manami Gake, Riku Matsubara, Takanori Shibata

    ORGANIC LETTERS   16 ( 22 ) 5980 - 5983  2014.11

     View Summary

    A Rh-catalyzed intermolecular [2 + 2 + 2] cycloaddition of the 2,3-double bond of benzothiophene dioxides with a,?-diynes gave sulfone-containing cycloadducts in high yields. This is the first example of a catalytic [2 + 2 + 2] cycloaddition that uses the 2,3-double bond of a heterole as an ene moiety. The consecutive reaction of benzodithiophene tetraoxide with 2,3-naphthylene-tethered 1,7-diyne gave an 11-ring condensed polycyclic compound in one pot.

    DOI

  • One-Pot Cross-Coupling of Diborylmethane for the Synthesis of Dithienylmethane Derivatives

    Kohei Endo, Takafumi Ishioka, Takanori Shibata

    SYNLETT   25 ( 15 ) 2184 - 2188  2014.09

     View Summary

    The one-pot palladium-catalyzed Suzuki-Miyaura cross-coupling reaction of a diborylmethane with bromothiophene derivatives realized the synthesis of various dithienylmethane derivatives. Cyclopentadithiophenes, which are promising compounds in material science, can be obtained in good yields. The in situ generation of an unstable thienylmethylboronate is a key step for the present reaction.

    DOI

  • Highly Chemo-, Enantio-, and Regioselective Synthesis of alpha,alpha-Disubstituted Furanones by Cu-Catalyzed Conjugate Addition

    Kohei Endo, Sayuri Yakeishi, Ryotaro Takayama, Takanori Shibata

    CHEMISTRY-A EUROPEAN JOURNAL   20 ( 29 ) 8893 - 8897  2014.07

     View Summary

    A highly chemo-, enantio-, and regioselective synthesis of furanones bearing an alpha,alpha- disubstituted quaternary stereogenic center is reported. The Cu-catalyzed enantioselective conjugate addition of organoaluminum reagents to unsaturated ketoesters at room temperature and subsequent lactonization took place. Synthetic transformations of furanones represent facile approaches to various cyclic or acyclic compounds bearing a quaternary stereogenic center.

    DOI PubMed

  • Ir(III)- Catalyzed C7-Position- Selective Oxidative C-H Alkenylation of Indolines with Alkenes in Air

    Shiguang Pan, Takayuki Wakaki, Naoto Ryu, Takanori Shibata

    CHEMISTRY-AN ASIAN JOURNAL   9 ( 5 ) 1257 - 1260  2014.05

     View Summary

    An efficient method for C7-position-selective alkenylation of N-substituted indolines with alkenes is reported. Various 7-alkenylindolines were obtained in moderate to excellent yields in air in the presence of catalytic amounts of [Cp*IrCl2](2), AgOTf, and Cu(OAc)(2). The protocol relies on the use of a carbonyl or carbamoyl group on the nitrogen atom of indoline as a directing group and is potentially applicable to the synthesis of 7-alkenylindoles and 7-alkylindoles.

    DOI PubMed

  • Directed C-H Alkenylation of Quinoline N-Oxides at the C-8 Position Using a Cationic Rhodium(I) Catalyst

    Takanori Shibata, Yusuke Matsuo

    ADVANCED SYNTHESIS & CATALYSIS   356 ( 7 ) 1516 - 1520  2014.05

     View Summary

    The cationic rhodium-catalyzed alkenylation proceeds at the C-8 position of quinoline N-oxides. Regioselective CH bond activation was achieved by the directing effect of the anionic oxygen of an N-oxide moiety, which can be readily removed by reductive treatment. A variety of 8-alkenylated quinoline N-oxides was obtained in moderate to high yields.

    DOI

  • Iridium-Catalyzed Enantioselective C H Alkylation of Ferrocenes with Alkenes Using Chiral Diene Ligands**

    Takanori Shibata, Tsubasa Shizuno

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   53 ( 21 ) 5410 - 5413  2014.05

     View Summary

    The first catalytic and enantioselective CH alkylation of ferrocene derivatives with various alkenes was achieved. A cationic iridium complex, having a chiral diene ligand, and an isoquinolyl moiety as a directing group are essential for regioselective and enantioselective CH bond activation.

    DOI

  • Iridium( I)-Catalyzed Direct C-H Bond Alkylation of the C-7 Position of Indolines with Alkenes

    Shiguang Pan, Naoto Ryu, Takanori Shibata

    ADVANCED SYNTHESIS & CATALYSIS   356 ( 5 ) 929 - 933  2014.03

     View Summary

    A cationic iridium-catalyzed C-7 alkylation of N-substituted indoline derivatives with various alkenes has been developed. A variety of 7-alkylindolines were obtained in moderate to high yields. This protocol relies on the use of the carbonyl group on the nitrogen atom of indoline as a directing group and it is potentially applicable to the large-scale synthesis of 7-alkylindoles.

    DOI

  • ENANTIOSELECTIVE SYNTHESIS OF PLANAR-CHIRAL PHOSPHINES WITH 1,N-DIOXAUVRARACYCLOPHANE SCAFFOLD AND THEIR APPLICATION AS CHIRAL LIGANDS

    Kazumasa Kanda, Shoya Oshima, Tsubasa Shizuno, Risa Hamanaka, Miku Fukai, Takanori Shibata

    HETEROCYCLES   88 ( 2 ) 1355 - 1370  2014.01

     View Summary

    A new family of chiral phosphines based on planar-chiral 1,n-dioxa[n]paracyclophane scaffold was created. They were synthesized with excellent enantioselectivity via asymmetric ortho-lithiation using sec-butyllithium and (-)-sparteine. These phosphines were used as 'chiral ligands in three reactions: Ag-catalyzed allylation of imines, Pd-catalyzed,asymmetric Sonogashira coupling of diiodoparacyclophanes, and Pd-catalyzed asymmetric Suzuki-Miyaura coupling of tricarbony1(eta(6)-ortho-dich1orobenzene)chromium.

    DOI

  • Asymmetric Cycloaddition Reactions

    T. Shibata

    Comprehensive Inorganic Chemistry II (Second Edition): From Elements to Applications   6   249 - 269  2013.08

     View Summary

    This chapter summarizes the recent work (published after 2000) of enantioseletive cycloadditions catalyzed by chiral Lewis acids and chiral transition metal complexes. The cycloaddition is categorized as [4+2], [5+2], [2+2], [2+2+2], [3+2], and [4+3] cycloadditions. These reactions provide efficient protocols for the construction of various chiral cyclic skeletons, which include central, axial, planar, and helical chiralities. © 2013 Elsevier Ltd. All rights reserved.

    DOI

  • BINAM-mono-PHOS as New Entry for Multinuclear Copper Catalysts in Asymmetric Conjugate Addition of Organozinc Reagents

    Kohei Endo, Ryotaro Takayama, Takanori Shibata

    SYNLETT   24 ( 9 ) 1155 - 1159  2013.06

     View Summary

    The readily functionalized ligands, BINAM-PHOS, participate in the copper-catalyzed asymmetric conjugate addition of organozinc reagents to enones. The incorporation of benzoyl derivatives on nitrogen atoms was crucial to promote the reaction. Notably, BINAM-PHOS derivatives gave the opposite major enantiomers to that obtained using BINOL-PHOS derivatives, which we have developed for the construction of multinuclear catalysts.

    DOI

  • Functionalized BINOL-mono-PHOS for Multinuclear Cu-Catalysts in Asymmetric Conjugate Addition of Organozinc Reagents

    Kohei Endo, Sayuri Yakeishi, Daisuke Hamada, Takanori Shibata

    CHEMISTRY LETTERS   42 ( 5 ) 547 - 549  2013.05

     View Summary

    Functionalization of BINOL-mono-PHOS achieved the Cu-catalyzed highly asymmetric conjugate addition of organozinc reagents to enones. The incorporation of a bulky hydroxy group at the 3'-position of BINOL-mono-PHOS dramatically improved the yield and enantioselectivity. The present novel BINOL-mono-PHOS ligands are effective in the Cu-catalyzed asymmetric conjugate addition of organozinc reagents in both acyclic enones and cyclohexenone.

    DOI

  • Recent Advances in Iridium-Catalyzed Alkylation of C-H and N-H Bonds

    Shiguang Pan, Takanori Shibata

    ACS CATALYSIS   3 ( 4 ) 704 - 712  2013.04

     View Summary

    Over the past few years, iridium complexes have been widely used in the direct functionalization of unactivated bonds. In the presence of iridium catalysts, inactive C-H and N-H bonds have been transformed into C-C and N-C bonds in dehydrative alkylation using alcohols, allylation using allyl carbonates, and alkylation using alkenes. Enantioselective variants of some reactions have also been reported.

    DOI

  • Ir(I)-Catalyzed Synthesis of N-Substituted Pyridones from 2-Alkoxypyridines via C-O Bond Cleavage

    Shiguang Pan, Naoto Ryu, Takanori Shibata

    ORGANIC LETTERS   15 ( 8 ) 1902 - 1905  2013.04

     View Summary

    A cationic Ir(I) complex-catalyzed O-to-N-alkyl migration in 2-alkoxypyridines bearing a secondary alkyl group on the oxygen atom by C-O bond cleavage is described. The present transformation gave various N-alkylpyridones in moderate to good yields. The addition of sodium acetate played a key role in suppressing beta-hydrogen elimination.

    DOI PubMed

  • Effect of Multinuclear Copper/Aluminum Complexes in Highly Asymmetric Conjugate Addition of Trimethylaluminum to Acyclic Enones

    Kohei Endo, Daisuke Hamada, Sayuri Yakeishi, Takanori Shibata

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   52 ( 2 ) 606 - 610  2013

     View Summary

    Al and friends: Asymmetric conjugate addition of Me3Al to β,β-disubstituted α,β-unsaturated ketones in the presence copper and L1 leads to a highly efficient construction of an all-carbon-substituted chiral quaternary center. This result is the first example of an asymmetric conjugate addition of Me3Al to acyclic enones to give a chiral quaternary carbon center with excellent yield and enantioselectivity under mild reaction conditions. Copyright © 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

    DOI

  • Cationic iridium-catalyzed synthesis initiated by the cleavage of C-H, N-H, and C-O bonds

    Takanori Shibata, Kyoji Tsuchikama, Shiguang Pan

    Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry   71 ( 11 ) 1182 - 1194  2013

     View Summary

    The direct functionalization of inactive bonds is an ideal transformation in organic synthesis because the introduction of activating groups, such as halogens and metals, to substrates is unnecessary and by-products derived from them are not formed. This report describes several types of cationic iridium-catalyzed reactions that occur through C-H, N-H, or C-O bond cleavage. The carbonyl-directed sp2 C-H bond activation of aryl ketones realized new approaches to benzofulvene, benzofuran and indole synthesis, as well as the C2-position-selective alkylation of N-acyl-protected indoles. The enantioselective sp3 C-H alkylation of 2-(alkylamino)pyridines and the intermolecular enantioselective hydroamination of heteroaromatic amines gave various chiral amines. 0-to-7V-alkyl migration in 2-alkoxypyridines gave 7V-alkylpyridones via C-O bond cleavage.

    DOI

  • Facile Synthesis of Cyclic Polyphenylenes by Consecutive Inter- and Intra-molecular Cycloadditions of ortho-, meta-, and para-Phenylene-Tethered Triynes

    Takanori Shibata, Masako Fujimoto, Hiroyuki Hirashima, Tatsuya Chiba, Kohei Endo

    SYNTHESIS-STUTTGART   44 ( 21 ) 3269 - 3284  2012.11

     View Summary

    Consecutive inter-and intramolecular [2+2+2] cycloadditions of various phenylene-tethered triynes were comprehensively studied by using chiral rhodium catalysts. ortho-Phenylene-tethered triynes gave chiral o,o,o,o-tetraphenylenes in high-to-excellent enantiomeric excess as dimers. meta-Phenylene-tethered triynes gave chiral o,m,o,m-tetraphenylenes in moderate enantiomeric excess as dimers along with hexaphenylenes as trimers. This is the first synthesis of cis-o,m,o,m-tetraphenylenes; one structure was ascertained by X-ray crystal structure analysis. para-Phenylene-tethered triynes gave o,p,o,p,o,p-hexaphenylenes as trimers along with the formation of o,p,o,p,o,p,o,p-octaphenylenes as tetramers.
    1 Introduction
    2 Results and Discussion
    2.1 ortho-Phenylene-Tethered Triynes
    2.2 Naphthylene-Tethered Triynes
    2.3 meta-Phenylene-Tethered Triynes
    2.4 para-Phenylene-Tethered Triynes
    3 Conclusion

    DOI

  • Cationic iridium-catalyzed enantioselective activation of secondary sp(3) C-H bond adjacent to nitrogen atom

    Shiguang Pan, Yusuke Matsuo, Kohei Endo, Takanori Shibata

    TETRAHEDRON   68 ( 44 ) 9009 - 9015  2012.11

     View Summary

    A cationic Ir(I)-tolBINAP complex catalyzed an enantioselective C-C bond formation, which was initiated by secondary sp(3) C-H bond cleavage adjacent to nitrogen atom. A wide variety of 2-(alkylamino) pyridines and alkenes were selectively transformed into the corresponding chiral amines with moderate to almost perfect enantiomeric excesses. Alkynes were also investigated as coupling partners. The effect of alkyl structure in substrates and directing groups were studied. This transformation represents the first example of a highly enantioselective C-H bond activation of a methylene group, not at allylic or benzylic position. (c) 2012 Elsevier Ltd. All rights reserved.

    DOI

  • Rh(III)-Catalyzed C-H Bond Activation along with "Rollover" for the Synthesis of 4-Azafluorenes

    Takanori Shibata, Satoshi Takayasu, Shun Yuzawa, Takashi Otani

    ORGANIC LETTERS   14 ( 19 ) 5106 - 5109  2012.10

     View Summary

    An intramolecular reaction of 3-alkynyl and 3-alkenyl-2-arylpyridines selectively gave 4-azafluorene compounds in the presence of a catalytic amount of [Cp*RhCl2](2) and Cu(OAc)(2). Pyridine-directed C-H bond activation along with "rollover" are likely to be key steps of this transformation.

    DOI

  • Ir(I)-Catalyzed C-H Bond Alkylation of C2-Position of Indole with Alkenes: Selective Synthesis of Linear or Branched 2-Alkylindoles

    Shiguang Pan, Naoto Ryu, Takanori Shibata

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   134 ( 42 ) 17474 - 17477  2012.10

     View Summary

    A cationic iridium-catalyzed C2-alkylation of N-substituted indole derivatives with various alkenes has been developed, which selectively gives linear or branched 2-alkylindoles in high to excellent selectivity. This protocol relies on the use of the carbonyl group on the nitrogen atom of indole as a directing group: a linear product was predominant when an acetyl group was used as a directing group, and a branched product was predominant with a benzoyl group.

    DOI PubMed

  • Rh(III)-catalyzed directed C-H bond amidation of ferrocenes with isocyanates

    Satoshi Takebayashi, Tsubasa Shizuno, Takashi Otani, Takanori Shibata

    BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY   8   1844 - 1848  2012.10

     View Summary

    [RhCp*(OAc)(2)(H2O)] [Cp* = pentamethylcyclopentadienyl] catalyzed the C-H bond amidation of ferrocenes possessing directing groups with isocyanates in the presence of 2 equiv/Rh of HBF4 center dot OEt2. A variety of disubstituted ferrocenes were prepared in high yields, or excellent diastereoselectivities.

    DOI

  • One-Pot Synthesis of Symmetrical and Unsymmetrical Diarylmethanes via Diborylmethane

    Kohei Endo, Takafumi Ishioka, Takahiro Ohkubo, Takanori Shibata

    JOURNAL OF ORGANIC CHEMISTRY   77 ( 17 ) 7223 - 7231  2012.09

     View Summary

    A one-pot synthesis of diarylmethanes from air-stable diborylmethane via the Suzuki-Miyaura cross-coupling reaction is described. The present approach realizes the synthesis of various symmetrical and unsymmetrical diarylmethanes in good to excellent yields.

    DOI PubMed

  • Reversal in enantioselectivity induced by achiral alcohols in asymmetric autocatalysis in the presence of a chiral diol as a chiral initiator

    Takanori Shibata, Hikaru Tarumi, Tsuneomi Kawasaki, Kenso Soai

    TETRAHEDRON-ASYMMETRY   23 ( 14 ) 1023 - 1027  2012.07

     View Summary

    A reversal in enantioselectivity was observed by the combination of a chiral diol and achiral alcohols as a chiral initiator in the asymmetric alkylation of a pyrimidine-5-carbaldehyde using diisopropylzinc. (2S,3S)-Butane-2,3-diol alone induced (R)-pyrimidyl alkanol, while a mixture of the chiral diol and phenol derivatives induced (S)-pyrimidyl alkanol. The effect of achiral alcohols is also discussed. (c) 2012 Elsevier Ltd. All rights reserved.

    DOI

  • [Ir(cod)(2)]BARF-Catalyzed C-H Bond Alkenylation and Alkylation of Ferrocenes

    Satoshi Takebayashi, Takanori Shibata

    ORGANOMETALLICS   31 ( 11 ) 4114 - 4117  2012.06

     View Summary

    [Ir(cod)(2)]BARF [BARF = tetrakis(3,5-trifluoromethylphenyl)borate] catalyzed the directed alkenylation and alkylation of ferrocenes to form a variety of tri- and disubstituted ferrocenes. Mechanistic investigation revealed several putative intermediates along with the importance of COD (1,5-cyclooctadiene), as a diene ligand, and a possible catalyst deactivation pathway. On the basis of the mechanistic investigation, catalytic activity was further improved.

    DOI

  • Detour and Direct Induction of Methyl-Containing Chiral Centers via Catalytic C-H or C-C Bond Formation

    Kohei Endo, Takanori Shibata

    SYNTHESIS-STUTTGART   44 ( 10 ) 1427 - 1452  2012.05

    Book review, literature introduction, etc.  

     View Summary

    The asymmetric induction of chiral centers bearing a methyl group is a fundamental protocol for the synthesis of valuable molecules in biologically active compounds. However, the direct asymmetric methylation is typically difficult to achieve. The present review describes recent representatives of detour and direct approaches to the construction of methyl-containing chiral centers via catalytic C-H or C-C bond formation.

    DOI

  • Multinuclear Cu-Catalysts Based on SPINOL-PHOS in Asymmetric Conjugate Addition of Organozinc Reagents

    Kohei Endo, Daisuke Hamada, Sayuri Yakeishi, Mika Ogawa, Takanori Shibate

    ORGANIC LETTERS   14 ( 9 ) 2342 - 2345  2012.05

     View Summary

    Multinuclear Cu/Zn complex-catalyzed efficient asymmetric conjugate addition of organozinc reagents to acyclic and cyclic enones has been developed in the presence of a wide variety of regioisomeric chiral diols bearing phosphorus moieties as ligands. The regioisomeric SPINOL-PHOS ligands based on a SPINOL architecture showed an unexpected inversion of stereoselectivity.

    DOI PubMed

  • Cross Coupling between sp(3)-Carbon and sp(3)-Carbon Using a Diborylmethane Derivative at Room Temperature

    Kohei Endo, Takahiro Ohkubo, Takafumi Ishioka, Takanori Shibata

    JOURNAL OF ORGANIC CHEMISTRY   77 ( 10 ) 4826 - 4831  2012.05

     View Summary

    A novel example of the Suzuki-Miyaura cross-coupling reaction between sp(3)-carbon and sp(3)-carbon is described. The reaction of a diborylmethane derivative with allyl halides or benzyl halides proceeded efficiently in the presence of appropriate Pd-catalysts at room temperature. The present approaches provide functionalized homoallylboronates and alkylboronates with excellent regio- and chemoselectivities.

    DOI

  • Non Chiral Pauson-Khand Reaction

    Takanori Shibata

    Pauson-Khand Reaction: Scope, Variations and Applications     49 - 68  2012.03

    DOI

  • Enantioselective synthesis of tripodal cyclophanes and pyridinophanes by intramolecular [2+2+2] cycloaddition

    Takanori Shibata, Mayu Miyoshi, Toshifumi Uchiyama, Kohei Endo, Nobuaki Miura, Kenji Monde

    TETRAHEDRON   68 ( 12 ) 2679 - 2686  2012.03

     View Summary

    An enantioselective intramolecular [2+2+2] cycloaddition of 2-aminophenol-tethered triynes and diyne-nitriles proceeded using the chiral Rh catalysts, and tripodal cyclophanes and pyridinophanes with a long ansa chain (up to [16]pyridinophane) were obtained in acceptable yield with high to almost perfect ee. In the reaction of triynes, we elucidated that the oxygen atom at the alkyne terminus is essential for the excellent enantioselectivity. For the construction of cage-type molecule, the choice of rigid tether, which connects 1,6-diyne moiety with a side carbon chain having alkyne or cyano group on its terminus, was important, and 8-amino-2-naphthol moiety was also a preferable tether. (C) 2012 Elsevier Ltd. All rights reserved.

    DOI

  • Ir(I)-Catalyzed Intermolecular Regio- and Enantioselective Hydroamination of Alkenes with Heteroaromatic Amines

    Shiguang Pan, Kohei Endo, Takanori Shibata

    ORGANIC LETTERS   14 ( 3 ) 780 - 783  2012.02

     View Summary

    A cationic Ir(I)-C-3-TUNEPHOS complex catalyzed an intermolecular hydroamination of styrene derivatives with various heteroaromatic amines. The reaction gave Markovnikov products with perfect regioselectivity and good enantioselectivity under solvent-free conditions.

    DOI PubMed

  • Asymmetric ortho-lithiation of 1,n-dioxa[n]paracyclophane derivatives for the generation of planar chirality

    Kazumasa Kanda, Risa Hamanaka, Kohei Endo, Takanori Shibata

    TETRAHEDRON   68 ( 5 ) 1407 - 1416  2012.02

     View Summary

    The asymmetric induction of planar chirality in 1,n-dioxa[n]paracyclophane derivatives via asymmetric ortho-lithiation is described. Enantioselective ortho-lithiation of unflippable 1,n-dioxa[n]paracyclophanes (n &lt;= 11) using sec-BuLi-(-)-sparteine at -78 degrees C and subsequent treatment with electrophiles gave the corresponding planar-chiral monosubstituted paracyclophanes with excellent ee. Further lithiation of these compounds and treatment with electrophiles gave planar-chiral paracyclophanes with two different substituents. Dilithiation of unflippable 1,n-dioxa[n]paracyclophanes gave the corresponding C(2)symmetrical disubstituted products with almost perfect ee. In the case of flippable 1,n-dioxa[n]paracyclophanes (n &gt;= 12), a stepwise reaction was required for the highly enantioselective formation of disubstituted products. (C) 2011 Elsevier Ltd. All rights reserved.

    DOI

  • Highly enantioselective synthesis of silahelicenes using Ir-catalyzed [2+2+2] cycloaddition

    Takanori Shibata, Toshifumi Uchiyama, Yusuke Yoshinami, Satoshi Takayasu, Kyoji Tsuchikama, Kohei Endo

    CHEMICAL COMMUNICATIONS   48 ( 9 ) 1311 - 1313  2012

     View Summary

    Silahelicenes, which contain two silole moieties in a helically chiral structure, were synthesized by a chiral Ir-catalyzed intermolecular [2 + 2 + 2] cycloaddition of tetraynes with diynes along with a Ni-mediated intramolecular [2 + 2 + 2] cycloaddition. The photophysical properties of the obtained highly enantiomerically enriched silahelicenes (up to 93% ee) were also measured.

    DOI

  • Ru-catalyzed beta-selective and enantioselective addition of amines to styrenes initiated by direct arene-exchange

    Maiko Otsuka, Hiroya Yokoyama, Kohei Endo, Takanori Shibata

    ORGANIC & BIOMOLECULAR CHEMISTRY   10 ( 19 ) 3815 - 3818  2012

     View Summary

    A catalytic beta-selective addition of amines to styrenes proceeded in the presence of cationic Ru complexes combined with diphosphine ligands. In the reaction of alpha-methylstyrene, an enantioselective addition was achieved by using xylylBINAP.

    DOI

  • Stereoselective Synthesis of Allylsilanes Bearing Tetrasubstituted Olefin via 2,2-Diborylethylsilane

    Kohei Endo, Akira Sakamoto, Takahiro Ohkubo, Takanori Shibata

    CHEMISTRY LETTERS   40 ( 12 ) 1440 - 1442  2011.12

     View Summary

    The regio- and stereoselective synthesis of allylsilane derivatives bearing a tetrasubstituted olefin was achieved using 2,2-diborylethylsilane as a key intermediate. The regioselective deprotonation of a 2,2-diborylethylsilane with LTMP and the subsequent nucleophilic addition to ketones gave corresponding allylsilanes in good to excellent yield with excellent stereoselectivity.

    DOI

  • Ir(III)-Catalyzed Room-Temperature Synthesis of Multisubstituted Benzofurans Initiated by C-H Activation of alpha-Aryloxy Ketones

    Taknori Shibata, Yu-Ki Hashimoto, Maiko Otsuka, Kyoji Tsuchikama, Kohei Endo

    SYNLETT   ( 14 ) 2075 - 2079  2011.09

     View Summary

    Cyclodehydration of various alpha-aryloxy ketones proceeded to give various multisubstituted benzofurans by using an Ir(III) catalyst, which was prepared from [Cp*IrCl2](2), AgSbF6, and Cu(OAc)(2). The use of the cationic iridium complex with a carboxylate salt realized the efficient transformation at ambient temperature.

    DOI

  • Cationic Ir(I)-Catalyzed sp(3) C-H Bond Alkenylation of Ureas with Alkynes for the Synthesis of 2,3-Disubstituted Indoles

    Takanori Shibata, Hiroyuki Hirashima, Mitsugu Kasagawa, Kyoji Tsuchikama, Kohei Endo

    SYNLETT   ( 15 ) 2171 - 2176  2011.09

     View Summary

    Secondary sp(3) C-H bond activation of ureas was achieved by a cationic Ir(I)-JOSIPHOS catalyst. Regioselective C-H bond cleavage adjacent to the nitrogen atom in N-benzylureas and an N-allyl urea possessing a 2-alkynylphenyl group, and subsequent intramolecular reaction with an alkyne along with double-bond isomerization provided 2,3-disubstituted indoles.

    DOI

  • Ir(I)-Catalyzed Enantioselective Secondary sp(3) C-H Bond Activation of 2-(Alkylamino)pyridines with Alkenes

    Shiguang Pan, Kohei Endo, Takanori Shibata

    ORGANIC LETTERS   13 ( 17 ) 4692 - 4695  2011.09

     View Summary

    A cationic Ir(1)-tolBINAP complex catalyzed an enantioselective C-C bond formation initiated by secondary sp(3) C-H bond cleavage adjacent to a nitrogen atom. The reaction of 2-(alkylamino)pyridines with various alkenes gave chiral amines In good yields with high enantiomeric excesses.

    DOI PubMed

  • Chemoselective Suzuki Coupling of Diborylmethane for Facile Synthesis of Benzylboronates

    Kohei Endo, Takahiro Ohkubo, Takanori Shibata

    ORGANIC LETTERS   13 ( 13 ) 3368 - 3371  2011.07

     View Summary

    The chemoselective Pd-catalyzed Suzuki-Miyaura cross-coupling reaction using a diborylmethane is reported. The use of an equimolar amount of base with a diborylmethane realized chemoselective coupling for the synthesis of various benzylboronate derivatives. Sterically hindered aryl bromides can give products in moderate to excellent yields.

    DOI

  • Regioselective Addition of Various Heteronucleophiles to (Styrene)Cr(CO)(3) Complexes

    Maiko Otsuka, Kohei Endo, Takanori Shibata

    ORGANOMETALLICS   30 ( 13 ) 3683 - 3685  2011.07

     View Summary

    (Styrene)Cr(CO)(3) complexes underwent the addition of various heteronucleophiles such as alcohols, amines, and thiols, in the presence of KOH, and the beta-addition products were selectively obtained in moderate to excellent yields. The structural details and features of the product complexes were also elucidated.

    DOI

  • New strategy for the cyclic polyphenylenes based on [2+2+2] cycloaddition of alkynes

    Takanori Shibata, Hiroyuki Hirashima, Masako Fujimoto, Tatsuya Chiba, Kohei Endo

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   241  2011.03

    Research paper, summary (international conference)  

  • Multinuclear Pd/Zn Complex-Catalyzed Asymmetric Alkylative Ring-Opening Reaction of Oxabicyclic Alkenes

    Kohei Endo, Keisuke Tanaka, Mika Ogawa, Takanori Shibata

    ORGANIC LETTERS   13 ( 5 ) 868 - 871  2011.03

     View Summary

    A multinuclear palladium catalyst can be used to realize the efficient catalytic asymmetric alkylative ring-opening reaction of oxabicyclic alkenes using dimethylzinc. The use of (R)-BINOL-PHOS bearing bisphosphine and diol moieties is essential for achieving excellent catalytic performance; the corresponding monophosphine and hydroxy-protected derivatives showed lower catalytic activities and/or enantioselectivities. The generation of Pd/Zn-multinuclear complexes is a key feature of the present catalysis.

    DOI

  • Enantioselective construction of new chiral cyclic scaffolds using [2+2+2] cycloaddition

    Takanori Shibata, Toshifumi Uchiyama, Hiroyuki Hirashima, Kohei Endo

    PURE AND APPLIED CHEMISTRY   83 ( 3 ) 597 - 605  2011

     View Summary

    Two types of enantioselective [2 + 2 + 2] cycloadditions of triynes using chiral rhodium catalysts are disclosed. The intramolecular reaction of ortho-aminophenol-tethered triynes provides chiral tripodal compounds. Consecutive inter- and intramolecular reactions of ortho-phenylene-tethered triynes provide chiral tetraphenylenes.

    DOI

  • Chiral Rh- and Ir-Catalyzed Intramolecular Cycloaddition of Hexaynes for the Construction of New Chiral Skeletons

    Takanori Shibata, Tatsuya Chiba, Hiroyuki Hirashima, Yasunori Ueno, Kohei Endo

    HETEROATOM CHEMISTRY   22 ( 3-4 ) 363 - 370  2011

     View Summary

    Enantioselective intramolecular cycloaddition of hexaynes with 1,3-diyne moiety was examined. Chiral Rh catalyst provided axially chiral 1,1&apos;-bis(biphenylenyl) derivatives by consecutive [2 + 2 + 2] cycloaddition. In contrast, chiral Ir catalyst provided axially chiral macrocyclic compounds with 1,3-diyne moiety by single [2 + 2 + 2] cycloaddition. (C) 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:363-370, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20691

    DOI

  • Facile Catalytic SNAr Reaction of Nonactivated Fluoroarenes with Amines Using eta(6)-Benzene Ruthenium(II) Complex

    Maiko Otsuka, Hiroya Yokoyama, Kohei Endo, Takanori Shibata

    SYNLETT   ( 17 ) 2601 - 2606  2010.10

     View Summary

    Catalytic SNAr reaction of fluoroarenes possessing no electron-withdrawing group(s) with cyclic amines was achieved using a readily accessible Ru catalyst, which was prepared from [Ru(benzene)Cl-2](2), AgOTf, and P(p-FC6H4)(3). The coexistence of molecular sieves MS4A realized high conversion and various substituted aryl amines were obtained in good to high yields.

    DOI

  • Chemoselective and Regiospecific Suzuki Coupling on a Multisubstituted sp(3)-Carbon in 1,1-Diborylalkanes at Room Temperature

    Kohei Endo, Takahiro Ohkubo, Munenao Hirokami, Takanori Shibata

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   132 ( 32 ) 11033 - 11035  2010.08

     View Summary

    The palladium-catalyzed Suzuki-Miyaura cross-coupling on a multisubstituted sp(3)-carbon in 1,1-diborylalkanes was achieved at room temperature. The generation of a monoborate intermediate by virtue of the adjacent B atom could result in the chemoselective coupling reaction under ambient conditions.

    DOI

  • Enantioselective Synthesis of Planar-Chiral 1,n-Dioxa[n]paracyclophanes via Catalytic Asymmetric ortho-Lithiation

    Kazumasa Kanda, Kohei Endo, Takanori Shibata

    ORGANIC LETTERS   12 ( 9 ) 1980 - 1983  2010.05

     View Summary

    Highly enantioselective ortho-lithiation and dilithiation of 1,n-dioxa[n]paracyclophanes were realized with the use of see-butyllithium and a catalytic or stoichiometric amount of sparteine. Quenching with various electrophiles, such as iodine, iodomethane, and chlorodiphenylphosphine, afforded chiral mono- and disubstituted paracyclophanes with good to excellent ee.

    DOI PubMed

  • Enantioselective Intramolecular [2+2+2] Cycloaddition of Dienynes for the Construction of Adjacent Three Chiral Centers

    Takanori Shibata, Mayumi Otomo, Kohei Endo

    SYNLETT   ( 8 ) 1235 - 1238  2010.05

     View Summary

    A chiral rhodium catalyst realized the first intramolecular [2+2+2] cycloaddition of yne-ene-enes, and chiral multicyclic cyclohexenes with adjacent three chiral centers were afforded with high to excellent ee.

    DOI

  • Stereoselective Synthesis of Tetrasubstituted Alkenylboronates via 1,1-Organodiboronates

    Kohei Endo, Munenao Hirokami, Takanori Shibata

    JOURNAL OF ORGANIC CHEMISTRY   75 ( 10 ) 3469 - 3472  2010.05

     View Summary

    The stereoselective synthesis of tetrasubstituted alkenylboronates was established via the lithiation/nucleophilic addition reaction of 1,1-orizanodiboronates to carbonyl compounds. The present approach enables the facile and practical synthesis of tetrasubstituted olefins, which are useful synthetic intermediates for further functionalizations.

    DOI PubMed

  • Asymmetric Amplification and Autocatalysis

    Kenso Soai, Tsuneomi Kawasaki, Takanori Shibata

    Catalytic Asymmetric Synthesis: Third Edition     891 - 930  2010.03

    DOI

  • Catalytic SNAr reaction of non-activated fluoroarenes with amines via Ru eta(6)-arene complexes

    Maiko Otsuka, Kohei Endo, Takanori Shibata

    CHEMICAL COMMUNICATIONS   46 ( 2 ) 336 - 338  2010

     View Summary

    Ru-catalyzed SNAr reaction of non-activated fluoroarenes with secondary amines proceeded through eta(6)-arene complexes to give aminated products in up to 79% yield.

    DOI

  • Multinuclear Catalyst for Copper-Catalyzed Asymmetric Conjugate Addition of Organozinc Reagents

    Kohei Endo, Mika Ogawa, Takanori Shibata

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   49 ( 13 ) 2410 - 2413  2010

     View Summary

    (Figure Presented) A whole lot o&#039; metal: An efficient copper-catalyzed asymmetric conjugate addition was achieved using a binol-derived ligand. The catalytic system has a turnover number of 2000, and the excellent cata-lytic performance could be attributed to the generation of a multinuclear complex such as 1. binol = 2, 2&#039;-dihydroxy-l, 1&#039;-binaphthyl. © 2010 Wiley-VCH Verlag GmbH &amp; Co. KGaA.

    DOI PubMed

  • Sequential Catalytic Reactions for the Synthesis of Benzofulvenes Using an Iridium Complex with Dual Function

    Kyoji Tsuchikama, Mitsugu Kasagawa, Kohei Endo, Takanori Shibata

    SYNLETT   ( 1 ) 97 - 100  2010.01

     View Summary

    The cationic iridium complex ([Ir(cod)(2)]OTf + rac-BINAP) efficiently catalyzed a sequential process of ortho-C-H bond functionalization, cyclization and dehydration, leading to a concise preparation of 1-methylene indene (benzofulvene) derivatives. The iridium complex operated as a catalyst in the ortho-C-H bond alkenylation of aryl ketones with alkynes and as a Lewis acid catalyst in the cyclization of the alkenylated product and the subsequent dehydration.

    DOI

  • Iridium-Catalyzed Selective Synthesis of 4-Substituted Benzofurans and Indoles via Directed Cyclodehydration

    Kyoji Tsuchikama, Yu-ki Hashimoto, Kohei Endo, Takanori Shibata

    ADVANCED SYNTHESIS & CATALYSIS   351 ( 17 ) 2850 - 2854  2009.11

     View Summary

    A directed cyclization-dehydration cascade of alpha-aryloxy ketones and alpha-arylamino ketones was efficiently catalyzed by a cationic iridium-BINAP complex, which afforded various types of 4-substituted benzofurans and indoles in high yields with complete regioselectivity. The newly developed protocol also enabled the enantioselective preparation of chiral 4-acetyloxindole using a chiral iridium catalyst.

    DOI

  • Enantioselective Synthesis of Chiral Tripodal Cage Compounds by [2+2+2] Cycloaddition of Branched Triynes

    Takanori Shibata, Toshifumi Uchiyama, Kohei Endo

    ORGANIC LETTERS   11 ( 17 ) 3906 - 3908  2009.09

     View Summary

    Cyclotrimerization of triynes branched by a nitrogen atom of 2-aminophenol yielded planar-chiral tripodal cage compounds. When a cationic Rh-Me-DUPHOS catalyst was used, the cycloadducts were obtained in high yield and excellent ee, and a macrocyclic compound with a [15]cyclophane system was also obtained. This method can be further applied to the synthesis of a triarmed pyridinophane by the intramolecular reaction of a diyne-nitrile.

    DOI

  • Iridium-Catalyzed Cycloadditions

    Takanori Shibata

    Iridium Complexes in Organic Synthesis     277 - 298  2009.07

    DOI

  • Synthesis of 1,1-Organodiboronates via Rh(I)Cl-Catalyzed Sequential Regioselective Hydroboration of 1-Alkynes

    Kohei Endo, Munenao Hirokami, Takanori Shibata

    SYNLETT   ( 8 ) 1331 - 1335  2009.05

     View Summary

    A Rh(I)Cl-DPPB-complex-catalyzed sequential hydroboration of aryl alkynes and aliphatic alkynes was achieved. The reaction proceeded with almost perfect regioselectivity to afford 1,1-organodiboronate compounds in moderate to good yield.

    DOI

  • Cationic Ir(I)-Catalyzed sp(3) C-H Bond Alkenylation of Amides with Alkynes

    Kyoji Tsuchikama, Mitsugu Kasagawa, Kohei Endo, Takanori Shibata

    ORGANIC LETTERS   11 ( 8 ) 1821 - 1823  2009.04

     View Summary

    A cationic Ir(I)-BINAP catalyst cleaved sp(3) C-H bonds of arylamides rather than sp(2) C-H bonds, which was followed by alkenylation with alkynes to give allylamides. Several types of amides and alkynes were suitable as substrates, and the corresponding allylamides were obtained in moderate to good yield. We also demonstrated that carbonyl-directed sp(3) C-H bond cleavage would be an initial step in the present reaction by a deuterium-labeling experiment.

    DOI

  • The first asymmetric Sonogashira coupling for the enantioselective generation of planar chirality in paracyclophanes

    Kazumasa Kanda, Tamami Koike, Kohei Endo, Takanori Shibata

    CHEMICAL COMMUNICATIONS   ( 14 ) 1870 - 1872  2009

     View Summary

    The double Sonogashira coupling of diiodoparacyclophanes with alkynes proceeded to give planarly chiral dialkynylparacyclophanes; a chiral Pd catalyst, which was prepared in situ from PdCl(2)(CH(3)CN)(2) and Taniaphos, realized the first asymmetric Sonogashira coupling with up to ca. 80% ee.

    DOI

  • Catalytic Enantioselective Synthesis of Chiral Tetraphenylenes: Consecutive Inter- and Intramolecular Cycloadditions of Two Triynes

    Takanori Shibata, Tatsuya Chiba, Hiroyuki Hirashima, Yasunori Ueno, Kohei Endo

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   48 ( 43 ) 8066 - 8069  2009

     View Summary

    Triynes having a phenylene-bridged 1,5-diyne moiety were transformed into substituted tetraphenylenes by the title sequence. A cationic Rh-ligand species catalyzed this highly enantioselective reaction. This protocol is a new and easy approach to the construction of the tetraphenylene skeleton and enables an efficient asymmetric synthesis (see scheme; R=H; Z=NTs, C(CO2Me) 2, O). © 2009 Wiley-VCH Verlag.

    DOI

  • Cationic iridium-BINAP complex-catalyzed addition of aryl ketones to alkynes and alkenes via directed C-H bond cleavage

    Kyoji Tsuchikama, Mitsugu Kasagawa, Yu-Ki Hashimoto, Kohei Endo, Takanori Shibata

    JOURNAL OF ORGANOMETALLIC CHEMISTRY   693 ( 26 ) 3939 - 3942  2008.12

     View Summary

    Cationic Ir complex ([Ir(cod)(2)]BF(4) + BINAP) catalyzed the addition of ortho-C-H bonds in aryl ketones to alkynes, which gave alkenylated products in good to high yield. Styrene derivatives were good substrates, and the enantioselective addition to norbornene was also described. (C) 2008 Elsevier B. V. All rights reserved.

    DOI

  • DMAP-Accelerated Rhodium(I) Chloride Catalyzed Hydroboration of Vinylarenes

    Kohei Endo, Munenao Hirokami, Kazunari Takeuchi, Takanori Shibata

    SYNLETT   ( 20 ) 3231 - 3233  2008.12

     View Summary

    Regioselective hydroboration of vinylarenes catalyzed by a Rh(I)-DPPB complex proceeded rapidly when DMAP was used as an additive. The catalyst loading could be reduced to 0.4 mol% Rh(I) to furnish the desired products in good to excellent yield with high regioselectivity.

    DOI

  • RHODIUM-CATALYZED INTRAMOLECULAR CYCLOADDITION OF CYCLOPROPENE-YNES TRIGGERED BY CABON-CARBON BOND CLEAVAGE

    Takanori Shibata, Shunsuke Maekawa, Kohei Tamura

    HETEROCYCLES   76 ( 2 ) 1261 - 1270  2008.11

     View Summary

    In the presence of a catalytic amount of RhCl(PPh(3))(3), an intramolecular cycloaddition of cyclopropene-yne proceeded along with carbon-carbon bond cleavage of cyclopropene ring to give various bicyclic cyclopentadiene derivatives in good to high yield.

    DOI

  • Counteranion-Accelerated Rh-I O Ac-Catalyzed Regioselective Hydroboration of Vinylarenes

    Kohei Endo, Munenao Hirokami, Takanori Shibata

    ORGANOMETALLICS   27 ( 20 ) 5390 - 5393  2008.10

     View Summary

    (RhOAc)-O-I shows a remarkably high catalytic activity for the hydroboration of vinylarenes with pinacolborane. The reaction was complete within 10 min to give the Markovnikov product.

    DOI

  • Iridium-catalyzed enantioselective formal [4+2] cycloaddition of biphenylene and alkynes for the construction of axial chirality

    Takanori Shibata, Go Nishizawa, Kohei Endo

    SYNLETT   ( 5 ) 765 - 768  2008.03

     View Summary

    Chiral iridium complex catalyzed a formal [4+2] cycloaddition of biphenylene with disubstituted alkynes, which was initiated by carbon-carbon bond cleavage. Axially chiral 9, 10-disubstituted phenanthrenes were enantiomerically obtained.

    DOI

  • Enantioselective syntheses of various chiral multicyclic compounds with quaternary carbon stereocenters by catalytic intramolecular cycloaddition

    Takanori Shibata, Yu-Ki Tahara, Kohei Tamura, Kohei Endo

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   130 ( 11 ) 3451 - 3457  2008.03

     View Summary

    The intramolecular cycloaddition of 1,n-diene-ynes (n = 4-6), where alkyne and alkene moieties are connected by a 1,1-disubstituted alkene, was examined using a chiral rhodium catalyst, and various types of cycloadducts with quaternary carbon stereocenter(s) were obtained in high to excellent enantiomeric excess. In the case of 1,4-diene-ynes, tricyclic, bicyclic, and spirocyclic compounds were obtained depending upon the substituents at the 2-position of the 1,4-diene moiety and those at their alkyne termini. On the other hand, 1,5- and 1,6-diene-ynes gave tricyclic and bicyclic compounds, which included medium-sized ring systems. The mechanistic considerations for different reaction pathways and the synthetic transformation of tricyclic products into functionalized spirocyclic compounds are also described. The reaction of enediynes, where two alkyne moieties are connected by a 1,1-disubstituted alkene, was also examined, and sterically strained tricyclic compounds with two carbon stereocenters were obtained.

    DOI PubMed

  • Carbonylative and hydrosilylative carbocyclization of 1,5-diynes for the synthesis of cyclic dienones

    Takanori Shibata, Naohisa Nakagawa, Yasunori Ueno, Kohei Endo

    ORGANOMETALLICS   27 ( 6 ) 1342 - 1344  2008.03

     View Summary

    A rhodium complex, [Rh(acac)(CO)(2)], has been identified to catalyze the cyclization of various 1,5-diynes with hydrosilanes under an atmospheric pressure of carbon monoxide at room temperature. The cyclization of 1,5-diynes proceeds along with hydrosilylation and carbonylation to give derivatives of 2,5-dialkylidenecyclopentanone.

    DOI

  • Rh-catalyzed intermolecular and enantioselective [4+2] cycloaddition of 1,3-dienes with dimethyl acetylenedicarboxylate

    Takanori Shibata, Daisuke Fujiwara, Kohei Endo

    ORGANIC & BIOMOLECULAR CHEMISTRY   6 ( 3 ) 464 - 467  2008.02

     View Summary

    A Rh-BINAP complex catalyzed an intermolecular and enantioselective [4 + 2] cycloaddition of 1-monosubstituted, 1, 1- or 1,2-disubstituted buta-1,3-dienes with dimethyl acetylenedicarboxylate to give chiral cyclohexa-1,4-dienes.

    DOI

  • Iridium-catalyzed consecutive and enantio selective [2+2+2] cycloaddition of tetraynes and hexaynes for the construction of an axially chiral biaryl system

    Takanori Shibata, Shiho Yoshida, Yoshikazu Arai, Maiko Otsuka, Kohei Endo

    TETRAHEDRON   64 ( 5 ) 821 - 830  2008.01

     View Summary

    A chiral iridium complex catalyzed a consecutive and enantioselective [2+2+2] cycloaddition of polyynes to give axially chiral compounds. Intermolecular reaction of tetraynes, possessing aryl groups on their termini, with protected but-2-yne-1,4-diols gave C-2-symmetrical quateraryl compounds. Intramolecular reaction of hexaynes, possessing aryl or alkyl groups on their termini gave C-2-symmetrical biaryl compounds. The catalytic synthesis of a pentacene derivative with axial chiralities is also discussed. (c) 2007 Published by Elsevier Ltd.

    DOI

  • Recent advances in enantioselective [2+2+2] cycloaddition

    Takanori Shibata, Kyoji Tsuchikama

    ORGANIC & BIOMOLECULAR CHEMISTRY   6 ( 8 ) 1317 - 1323  2008

     View Summary

    Enantioselective cycloaddition using chiral transition metal catalysts is an atom-economical and efficient synthetic tool for the construction of chiral carbo- and heterocyclic skeletons. This short account discloses our recent results of inter- and intramolecular enantioselective [2 + 2 + 2] cycloadditions of alkyne and/or alkene moiety(ies). Chiral iridium complexes catalyzed the alkyne trimerization for the generation of axial chirality(ies), and chiral rhodium ones catalyzed alkyne-alkyne-alkene cyclization for the generation of a quaternary carbon including spirocyclic system.

    DOI PubMed

  • Highly diastereo- and enantioselective construction of both central and axial chiralities by Rh-catalyzed [2+2+2] cycloaddition

    Takanori Shibata, Mayumi Otomo, Yu-ki Tahara, Kohei Endo

    ORGANIC & BIOMOLECULAR CHEMISTRY   6 ( 23 ) 4296 - 4298  2008

     View Summary

    The cationic Rh-SEGPHOS complex catalyzed an intermolecular [2 + 2 + 2] cycloaddition of enynes, possessing an ortho-substituted aryl group on their alkyne terminus, with acetylenedicarboxylates. Bicyclic cyclohexa-1,3-dienes with both central and axial chiralities were obtained in extremely highly diastereo- and enantioselective manner.

    DOI

  • Rhodium-catalyzed enantioselective [2+2+2] cycloaddition of diynes with unfunctionalized alkenes

    Takanori Shibata, Ai Kawachi, Mika Ogawa, Yusuke Kuwata, Kyoji Tsuchikarna, Kohei Endo

    TETRAHEDRON   63 ( 52 ) 12853 - 12859  2007.12

     View Summary

    A chiral rhodium complex catalyzed an enantioselective [2+2+2] cycloaddition of unsymmetrical diynes with norbornene, and tetracyclic products were obtained in good to excellent cc. The cycloaddition of a symmetrical diyne with styrene derivatives as coupling partners gave bicyclic products in good cc. (c) 2007 Elsevier Ltd. All rights reserved.

    DOI

  • Thermal and au(I)-catalyzed intramolecular [4+2] cycloaddition of aryl-substituted 1,6-diynes for the synthesis of biaryl compounds

    Takanori Shibata, Ryo Fujiwara, Daisuke Takano

    SYNLETT   ( 17 ) 2766 - 2766  2007.10

    Other  

  • Highly enantioselective intramolecular [2+2+2] cycloaddition of enediynes and dienynes

    Takanori Shibata, Yu-Ki Tahara, Kouhei Tamura

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   234  2007.08

    Research paper, summary (international conference)  

  • Rh-catalyzed cyclization of diynes and enynes initiated by carbonyl-directed activation of aromatic and vinylic C-H bonds

    Kyoji Tsuchikama, Yusuke Kuwata, Yu-Ki Tahara, Yusuke Yoshinami, Takanori Shibata

    ORGANIC LETTERS   9 ( 16 ) 3097 - 3099  2007.08

     View Summary

    [GRAPHICS]
    The Rh-catalyzed hydroarylative and hydrovinylative cyclization of diynes with aryl ketones or enones gave monocyclic 1,3-dienes. Enynes also underwent the same reaction and chiral products were obtained with high ee using a chiral Rh catalyst. Carbonyl-directed activation of aromatic and vinylic C-H bonds is likely the initial step in the present transformation.

    DOI

  • Chiral secondary alcohol-induced asymmetric autocatalysis: correlation between the absolute configuration of the chiral initiators and the product

    Takanori Shibata, Kimiko Iwahashi, Tsuneomi Kawasaki, Kenso Soai

    TETRAHEDRON-ASYMMETRY   18 ( 15 ) 1759 - 1762  2007.08

     View Summary

    In the presence of various chiral secondary alcohols as chiral initiators, an enantioselective alkylation of a pyrimidine-5-carbaldehyde using diisopropylzinc was examined: a pyrimidyl alkanol was obtained in high yield and enantiomeric excess. The correlation between the absolute configuration of the chiral secondary alcohols and the pyrimidyl alkanol is discussed. (C) 2007 Elsevier Ltd. All rights reserved.

    DOI

  • Enantioselective intramolecular [2+2+2] cycloaddition of enediynes for the synthesis of chiral cyclohexa-1,3-dienes

    Takanori Shibata, Hiroshi Kurokawa, Kazumasa Kanda

    JOURNAL OF ORGANIC CHEMISTRY   72 ( 17 ) 6521 - 6525  2007.08

     View Summary

    The enantioselective intramolecular [2 + 2 + 2] cycloaddition of various enediynes, where two acetylenic moieties are connected by a traps-olefinic moiety, gave chiral tricyclic cyclohexa-1,3-dienes using Rh-H-8-BINAP catalyst. In the case of carbon-atom-tethered enediynes, enantioselectivity was generally good-to-high regardless of the substituents on their alkyne termini. In contrast, with heteroatom-tethered enediynes, appropriate substituents were required to induce the oxidative coupling of alkyne and alkene moieties before that of two alkyne moieties, which would be important for highly enantioselective intramolecular cycloaddition.

    DOI

  • Rhodium-complex-catalyzed [2+2+2]cycloaddition of diynes and carbonyl compounds

    Kyoji Tsuchikama, Yusuke Yoshinami, Takanori Shibata

    SYNLETT   ( 9 ) 1395 - 1398  2007.06

     View Summary

    A Rh-BINAP complex was used to catalyze the hetero-[2+2+2] cycloaddition of symmetrical 1,6-diynes and carbonyl moiety of ketoesters, a diketone, and an aldehyde to give bicyclic alpha-pyrans, which were readily transformed into monocyclic compounds via the following electrocyclic ring opening. In the reaction of an unsymmetrical 1,6-diyne and a 1,7-diyne, alpha-pyrans with a quaternary carbon stereocenter were obtained in moderate to excel lent ee using a chiral rhodium catalyst.

    DOI

  • Iridium-catalyzed enantioselective [2+2+2] cycloaddition of diynes and monoalkynes for the generation of axial chiralities

    Takanori Shibata, Yoshikazu Arai, Kyoko Takami, Kyoji Tsuchikama, Takayoshi Fujimoto, Satoshi Takebayashi, Kentaro Takagi

    ADVANCED SYNTHESIS & CATALYSIS   348 ( 16-17 ) 2475 - 2483  2006.11

     View Summary

    A highly enantioselective intermolecular [2+2+2] cycloaddition of alkynes was catalyzed by a chiral iridium complex. Symmetrical and unsymmetrical diynes, and monoalkynes possessing functional group(s) were subjected to the reaction and various types of axially chiral compounds possessing biaryl skeletons were obtained in good to excellent enantiomeric excesses.

    DOI

  • Recent advances in the catalytic Pauson-Khand-type reaction

    Takanori Shibata

    ADVANCED SYNTHESIS & CATALYSIS   348 ( 16-17 ) 2328 - 2336  2006.11

    Book review, literature introduction, etc.  

     View Summary

    The Pauson-Khand-type reaction is formally a [2 + 2 + 1] cycloaddition involving an alkyne, an alkene and carbon monoxide catalyzed or mediated by transition metal complexes. This review focuses on the catalytic reaction and describes the recent research on the Pauson-Khand-type reaction.

    DOI

  • Highly enantioselective construction of a chiral spirocyclic structure by the [2+2+2] cycloaddition of diynes and exo-methylene cyclic compounds

    Kyoji Tsuchikama, Yusuke Kuwata, Takanori Shibata

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   128 ( 42 ) 13686 - 13687  2006.10

     View Summary

    The enantioselective [2 + 2 + 2] cycloaddition of 1,6-diynes with α-methylene lactones and cyclic ketones gave various chiral spirocyclic compounds. The reaction proceeded with high enantioselectivity when the rhodium-xylylBINAP complex was used as a chiral catalyst. Not only exo-methylene cyclic compounds but also exo-methylene acyclic compounds could be used as coupling partners for diynes. The present protocol provides access to a new chiral library possessing a quaternary carbon center, including a spirocyclic system. Copyright © 2006 American Chemical Society.

    DOI

  • ORGN 303-Enantioselective intramolecular cycloaddition of 1,4-diene-ynes for the construction of quaternary carbon centers

    Takanori Shibata, Yu-ki Tahara

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   232  2006.09

    Research paper, summary (international conference)  

  • Enantioselective intramolecular [2+2+2] cycloaddition of 1,4-diene-ynes: A new approach to the construction of quaternary carbon stereocenters

    Takanori Shibata, Yu-ki Tahara

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   128 ( 36 ) 11766 - 11767  2006.09

     View Summary

    The intramolecular [2 + 2 + 2] cycloaddition of various 1,4-diene-ynes was examined using a chiral rhodium catalyst. In the case of 1,4-diene-ynes with a substituent at the 2-position of the 1,4-diene moiety, tricyclic compounds possessing a strained bicyclo[2.2.1]heptene skeleton with two quaternary carbon stereocenters were obtained in high enantiomeric excess. On the other hand, in the case of 1,4-diene-ynes with no substituent at this position, bicyclic cyclohexa-1,3-dienes with a quaternary carbon stereocenter were obtained probably by carbon-carbon bond cleavage of the reaction intermediate. Copyright © 2006 American Chemical Society.

    DOI

  • Novel Rh catalysis in cross-coupling between alkyl halides and arylzinc compounds possessing ortho-COX (X = OR, NMe2, or Ph) groups

    Hideki Takahashi, Shinya Inagaki, Yasushi Nishihara, Takanori Shibata, Kentaro Takagi

    ORGANIC LETTERS   8 ( 14 ) 3037 - 3040  2006.07

     View Summary

    [GRAPHICS]
    Rh-dppf was found to be an efficient catalyst for the cross-coupling between primary alkyl halides bearing beta-hydrogens and arylzinc compounds possessing carbonyl groups such as ester, amide, or ketone at the ortho position. Various functional groups such as ester, nitrile, or acyloxylate moieties on the halides were tolerated under the catalysis conditions. Arylzinc compounds free of ortho-carbonyl groups reacted well with ethyl 3-iodopropanoate, suggesting that the essential intramolecular interaction between carbonyl groups and Rh promotes the reductive elimination.

    DOI

  • Cationic Au(I)- and Pt(II)-catalyzed silylation of alcohols using allylsilanes

    Takanori Shibata, Kazumasa Kanda, Yasunori Ueno, Ryo Fujiwara

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   79 ( 7 ) 1146 - 1147  2006.07

     View Summary

    The silylation of alcohols using allylsilanes was catalyzed by cationic Au(I) and Pt(II) species, which were prepared in situ from the metal chlorides ([AuC(PPh3)] PtCl2) and a silver salt. TBS-, TES-, and TIPS-protections of various alcohols and carboxylic acids could be possible.

    DOI

  • Rh-catalyzed enantioselective [2+2] cycloaddition of alkynyl esters and norbornene derivatives

    T Shibata, K Takami, A Kawachi

    ORGANIC LETTERS   8 ( 7 ) 1343 - 1345  2006.03

     View Summary

    The enantioselective [2 + 2] cycloaddition of alkynes possessing an ester functionality and norbornene derivatives proceeded efficiently using a chiral rhodium catalyst. The chiral tri- and tetracyclic cyclobutenes were obtained in moderate to high ee.

    DOI

  • Cationic Au(I)-catalyzed cycloisomerization of aromatic enynes for the synthesis of substituted naphthalenes

    T Shibata, Y Ueno, K Kanda

    SYNLETT   ( 3 ) 411 - 414  2006.02

     View Summary

    A cationic Au(I) complex catalyzed the cycloisomerization of aromatic enynes that possess a substituent on their alkyne terminus. Cyclization of the 6-endo-dig type proceeded dominantly to give 1,3-di- and 1,2,3-tri substituted naphthalenes.

    DOI

  • Enantioselective intramolecular [2+2+2] cycloaddition of triynes for the synthesis of atropisomeric chiral ortho-diarylbenzene derivatives

    T Shibata, K Tsuchikama, M Otsuka

    TETRAHEDRON-ASYMMETRY   17 ( 4 ) 614 - 619  2006.02

     View Summary

    An iridium-chiral diphosphine complex was used to catalyze an enantioselective [2+2+2] cycloaddition of oxygen- and nitrogen-bridged triynes with ortho-substituted aryl groups on their termini. ortho-Diarylbenzenes with atropisomeric chiralities were obtained in high yield and enantiomeric excess. (c) 2006 Elsevier Ltd. All rights reserved.

    DOI

  • Iridium and rhodium complex-catalyzed cycloadditions

    Takanori Shibata

    Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry   64 ( 9 ) 913 - 922  2006

     View Summary

    Transition metal-catalyzed cycloaddition is an atom-economical and powerful synthetic tool for the construction of cyclic carbon skeletons. Various types of cycloadditions, including [2 + 2 + 1], [2 + 2 + 2], [4 + 2] cycloaddition, etc., have been reported. Their asymmetric versions using chiral transition metal catalysts have also been reported to give enantiomerically-enriched multi-cyclic compounds. First, an iridium-catalyzed enantioselective Pauson-Khand-type reaction is summarized. Pauson-Khand(-type) reaction is a [2 + 2 + 1] cycloaddition of an alkyne, alkene and carbon monoxide, and gives synthetically useful cyclopentenones. Rhodium- and iridium-catalyzed Pauson-Khand-type reactions using an aldehyde as a CO source were also mentioned. Second, two types of enantioselective [2 + 2 + 2] cycloadditions are described: One is an iridium-catalyzed [2 + 2 + 2] cycloaddition of diynes and monoalkynes for the synthesis of chiral teraryls with two axial chiralities. Another is a rhodium-catalyzed [2 + 2 + 2] cycloaddition of enynes and monoalkynes for the synthesis of bicyclic cyclohexa-1, 3-dienes with a chiral quaternary carbon center. Third, a rhodium-catalyzed enantioselective [2 + 2] cycloaddition of alkynes and alkenes for the synthesis of chiral cyclobutenes is mentioned.

    DOI

  • Organic field-effect transistor based on a thin film of polydiacetylene prepared from 10,12-pentacosadiynoic acid

    T Koyanagi, M Muratsubaki, Y Hosoi, T Shibata, K Tsutsui, Y Wada, Y Furukawa

    CHEMISTRY LETTERS   35 ( 1 ) 20 - 21  2006.01

     View Summary

    The organic field-effect transistors based on polydiacetylene as an active semiconductor have been made. The hole mobility and the on/off ratio have been determined to be 1.3 x 10(-3) cm(2)/V s and 1.0 x 10(4), respectively, for the transistor based on the blue phase of polydiacetylene prepared from 10, 12-pentacosadiynoic acid. The gate-voltage-induced infrared absorption spectrum has been attributed to the positive carriers injected by field effect. The spectrum shows a remarkable electron-molecular vibration coupling between vibration levels and an electronic transition.

    DOI

  • Synthesis of functionalized benzylsilanes from arylzinc compounds and (iodomethyl)trimethylsilane by means of a novel Rh catalysis

    H Takahashi, KM Hossain, Y Nishihara, T Shibata, K Takagi

    JOURNAL OF ORGANIC CHEMISTRY   71 ( 2 ) 671 - 675  2006.01

     View Summary

    [GRAPHICS]
    The catalytic activity of a Rh complex in cross-coupling between ArZnI and TMSCH2I was examined in which the Rh complex, generated in situ from [RhCl(1,5-cyclooctadiene)](2) and 1,1'-bis(diphenylphosphino)ferrocene, exhibited excellent catalytic activity for the production of various functionalized benzylsilanes in good yields. From P-31 NMR studies of various solutions containing several of the reaction components, confirmation of the rapid and quantitative transfer of aryl groups from ArZnI to the Rh complex to form arylrhodium species was ascertained. A catalytic cycle, commencing with the transmetalation, was thus proposed for the reaction.

    DOI

  • アルキンの不斉付加

    柴田 高範

    ファルマシア   39 ( 7 ) 676 - 677  2003.07

    CiNii

  • Rhodium complex-catalyzed intramolecular ene-type reaction of allenynes

    Takanori Shibata, Yuri Takesue, Sho Kadowaki, Kentaro Takagi

    Synlett     268 - 270  2003.03

     View Summary

    Wilkinson&#039;s catalyst [RhCl(PPh3)3] catalyzed a cycloisomerization of allenynes which possess geminal methyls on the allene terminus and an intramolecular ene-type reaction proceeded to give various cross-conjugated trienes. Thermal Diels-Alder reaction of the obtained triene was examined to give a bicyclic compound in a high yield.

  • Catalytic Pauson-Khand-(type) reactions

    Takanori Shibata

    Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry   61 ( 9 ) 834 - 842  2003

     View Summary

    The Pauson-Khand(-type) reaction is a [2+2+1] cycloaddition of an alkyne, alkene and carbon monoxide, which gives synthetically useful cyclopentenones. The carbonylative coupling is mediated or catalyzed by various transition metal complexes. This review summarizes the recent advances in the catalytic Pauson-Khand(-type) reaction.

    DOI

  • Palladium-catalyzed synthesis of 2,2-dimethyl-3-pyrrolines from alpha-aminoallene and aryl iodides

    T Shibata, S Kadowaki, K Takagi

    HETEROCYCLES   57 ( 12 ) 2261 - 2266  2002.12

     View Summary

    Palladium-catalyzed cyclization of dimethyl-substituted allene possessing amino functionality with aryl iodides efficiently proceeded in the presence of diisopropylethylamine to give 2,2-dimethyl-3-aryl-3-pyrrolines. Under an atmospheric pressure of carbon monoxide, 3-aroyl-3-pyrrolines are provided in good yield.

    DOI

  • Enantioselective addition of dialkylzincs to N-diphenylphosphinylimines using polymer-supported N,N-dialkylnorephedrines as chiral ligands (pg 2757, 1997)

    T Suzuki, T Shibata, K Soai

    JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1   ( 19 ) 2207 - 2207  2002

    Other  

    DOI

  • Asymmetric autocatalysis - Discovery and development

    Kenso Soai, Takanori Shibata, Itaru Sato

    Nippon Kagaku Kaishi / Chemical Society of Japan - Chemistry and Industrial Chemistry Journal   2001 ( 3 ) 141 - 149  2001

     View Summary

    The asymmetric autocatalysis is an enantioselective synthesis where the asymmetric catalyst and the product possess the same structure and the same absolute configuration. We disclosed chiral α-isopropyl-3-pyridinemethanols, α-isopropyl-5-pyrimidinemethanols, and α-isopropyl-3-quinolinemethanols operate as asymmetric autocatalysts in the enantioselective additions of i-Pr2Zn to 3-pyridinecarbaldehyde, 5-pyrimidinecarbaldehyde and 3-quinolinecarbaldehyde, respectively. Especially, practically perfect asymmetric autocatalysis (&gt
    99% yield and &gt
    99.5%e.e.) is attained by using 2-(3,3-dimethyl-1-butynyl)-α-isopropyl-5-pyrimidinernethanol as an asymmetric autocatalyst. Moreover, consecutive asymmetric autocatalytic reaction enables α-isopropyl-5-pyrimidine- and α-isopropyl-3-quinolinemethanols as well as 5-(1-hydroxy-2-methylpropyl)pyridine-3-carboxamides with extremely low e.e. to automultiply with dramatic amplification of e.e. without any assistance of other chiral auxiliaries. It was also found that various chiral compounds can operate as chiral initiators in the enantioselective addition of i-Pr2Zn to 5-pyrimidinecarbaldehydes and α-isopropyl-5-pyrimidinemethanols with high e.e. were obtained. For example, in the presence of L-leucine with 2%e.e., asymmetric autocatalysis affords an (R)-α-isopropyl-5-pyrimidinemethanol with high e.e. It is known that asymmetric degradation of racemic leucine using circularly polarized light (CPL) gives chiral leucine (ca. 2%e.e.). Thus, asymmetric autocatalysis with amplification of e.e. serves as a correlation between CPL and highly enantiomerically enriched organic molecules. Moreover, enantiomorphic inorganic crystals such as quartz (SiO2) and sodium chlorate (NaClO3) can be utilized as chiral initiators and an α-isopropyl-5-pyrimidinemethanols with high e.e. was obtained in high yields.

    DOI

  • A new synthetic method to biaryls from arylzinc iodides using N-chloro-succinimide and a catalytic amount of palladium

    K. M. Hossain, T. Shibata, K. Takagi

    Synlett     1137 - 1138  2000.09

     View Summary

    Homo-coupling reactions of aryl- or alkynylzinc iodides were achieved by the use of N-chlorosuccinimide as an oxidant of zinc compounds in the presence of a catalytic amount of Pd.

    DOI

  • Synthesis of chiral alpha-acetoxy-(N)under-bar-acetylamides from chiral pyrimidylalkanols by the oxidative cleavage of pyrimidine ring

    S Tanji, Y Kodaka, T Shibata, K Soai

    HETEROCYCLES   52 ( 1 ) 151 - 158  2000.01

     View Summary

    Acetates of chiral 5-pyrimidylalkanols are transformed into chiral a acetoxy-N-acetylamides and alpha-acetoxyamides without racemization in high total yields by the oxidative cleavage of pyrimidine ring using ruthenium tetroxide.

  • Asymmetric synthesis of 3-quinolylalkylamine by enantioselective alkylation of w-diphenyl-phosphinyl-3-quinolylimine using chiral β-amino alcohols

    Tadakatsu Hayase, Shunji Osanai, Takanori Shibata, Kenso Soai

    Heterocycles   48   139 - 144  1998.12

     View Summary

    Chiral N-diphenylphosphiny 1-3-quinoly lamines (DPP amines) with up to 74.9% e.e. were obtained by the enantioselective alkylation using dialkylzincs in the presence of various chiral amino alcohols. The acidic hydrolysis of the chiral DPP amine afforded optically active chiral 3-quinolylamine without racemization.

  • A catalytic and enantioselective cyclopropylation of aldehydes using dicyclopropylzinc

    T Shibata, H Tabira, K Soai

    JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1   ( 2 ) 177 - 178  1998.01

     View Summary

    Enantioselective cyclopropylation of various aldehydes proceeds using dicyclopropylzine in the presence of a catalytic amount of chiral amino alcohol or thiophosphoramidate with Ti(OPri)(4) to provide enantiomerically enriched cyclopropyl alkanols (up to 96.6% ee).

    DOI

  • Enantioselective addition of dialkylzincs to N-diphenylphosphinylimines using polymer-supported N,N-dialkylnorephedrines as chiral ligands

    T Suzuki, T Shibata, K Soai

    JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1   ( 18 ) 2757 - 2760  1997.09

     View Summary

    Chiral N,N-dialkylnorephedrines supported on polystyrene resin catalyse the enantioselective addition of dialkylzincs to N-diphenylphosphinylimine, affording optically active N-diphenylphosphinylamines with high enantiomeric excess, The influence on the enantioselectivity of the carbon-chain spacer between the chiral function and polymer resin has been examined. Reaction temperature- and solvent-dependency on the chiral polymer-catalysed reaction has also been examined.

    DOI

  • BF3.OET2 CATALYZED [4+2] CYCLOADDITION REACTIONS OF N-ARYL SCHIFF-BASES WITH 1-ALKENYL, 1,2-PROPADIENYL, AND 1-ALKYNYL SULFIDES

    K NARASAKA, T SHIBATA

    HETEROCYCLES   35 ( 2 ) 1039 - 1053  1993.05

     View Summary

    [4+2] Cycloaddition reaction proceeds between N-aryl Schiff's bases and I-alkenyl sulfides, a 1,2-propadienyl sulfide, or 1-alkynyl sulfides in the presence of BF3.OEt2 to provide 2-substituted quinoline derivatives. A 2-alkyl-4-quinolone alkaloid, leptomerine, is prepared by applying the present cycloaddition reaction.

    DOI

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Syllabus

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Sub-affiliation

  • Faculty of Science and Engineering   Graduate School of Advanced Science and Engineering

Research Institute

  • 2022
    -
    2024

    Waseda Research Institute for Science and Engineering   Concurrent Researcher

Internal Special Research Projects

  • π−π相互作用により誘起されるキラリティを有するC3対称化合物の合成と評価

    2023  

     View Summary

     ディスプレイや照明、あるいは色素を具現化し得る基盤材料のひとつが「発光性有機分子」であり、新規な機能性有機化合物の開発が活発に行われている。一方最近、キラルな光である円偏光発光(CPL)が、次世代の高輝度液晶ディスプレイの光源や新規な光情報通信の基盤技術として注目されており、「円偏光発光材料としての低分子有機化合物」の開発が強く求められている。本研究では、強いπ–π相互作用に起因するC3対称を有する新規なプロペラ型キラル化合物の不斉合成と光基礎物性の評価を目的した。 すなわち、ヘキサアザトリナフチレン(HATNA)を堅固なπ共役平面を有する中心核として選択し、その周辺に可動性が制限された芳香環部位を導入する。立体的に近い位置に芳香環を強制的に配置することで、分子内でより強いπ–π相互作用を誘起させ、その立体的な歪みに由来するC3対称な不斉空間を創出する。そこで今回報告者は、アリールアルキンを導入することで、空間的に接近する2つのアリール基間に強いπ-π 相互作用をもつ化合物を合成し、置換基による光基礎物性を調査した。3,6-Dibromobenzene-1,2-diamineとhexaketocyclohexaneの縮合環化により6臭化物を生成し、続くアルキンとの6連続薗頭カップリングで 6 つのアリールアルキニル基を導入した HATNA化合物の合成に成功した。アルキン上の置換基として置換フェニル基、ナフチル基、キノリル基、ピリジル基の検討を行い、溶液、固体状態での光学特性を測定し、可視光で吸収が確認され、波長365 nmの光照射で、強い蛍光を観測した。 今後得られた強い発光特性を有するC3対称化合物を光学分割し、キロプティカル特性を測定する予定である。

  • C-H結合活性化とチェーンウォーキングによる遠隔位への官能基導入と不斉合成

    2022  

     View Summary

    遷移金属触媒を用いたC–C二重結合の異性化もよく知られたプロセスであり、特に、炭素鎖に沿って連続的に異性化することは、「チェーンウォーキング」と呼ばれ、この戦略は近年有機合成に利用されている。我々は、C–H活性化とチェーンウォークを融合させ、様々なアルケンを用いた遠隔官能基化の簡便な手法を実現した。配向基としてイミノ基を用い、イリジウム触媒の配位子としてジホスフィン配位子BINAPを用いた場合、官能基を末端に持つ直鎖アルキル鎖を、官能基を持つアルケンとの反応によってオルト位に設置することができた。本反応は、官能基耐性が高く、広い基質で適用可能であった。

  • らせん不斉を有する含硫黄ヘリセン化合物の触媒的かつエナンチオ選択的合成

    2022  

     View Summary

    本研究では、Rh触媒を用いたトリインと硫黄含有テザーとの分子内[2 + 2 + 2]環化付加反応によりジチア[5]ヘリセンの合成とチア[6]ヘリセンのエナンチオ選択的合成を達成した。ジアリール置換ジチア[5]ヘリセンを高収率から優れた収率で得ることができ、その環状体のScholl反応により、さらにπ−拡張を実現することができた。キラルRh触媒を用いることで、らせん不斉を有するキラル二置換チア[6]ヘリセンを高収率および高鏡像体過剰率で不斉合成することができた。これは、キラル金触媒を用いたチアヘリセンの環化異性化反応に続く、触媒的かつエナンチオ選択的な合成例である。

  • アルキンを配向基かつ反応部位として用いた多環式芳香族炭化水素の効率合成

    2021  

     View Summary

    本研究では、アルキンを配向基かつ反応部位として用いるビフェニレンの炭素−炭素結合開裂を伴った[4+2]付加環化において、キラルなジカチオン性二価白金錯体が、極めて活性な触媒として機能することを見いだした。さらに、本触媒反応おいて、Pt(II)/(IV)のレドックスサイクルで、反応が進行していることを実験的、ならびに計算化学的な両面から確認した。2価白金錯体を用いる反応は、一般的に価数の変化を伴わない触媒サイクルが一般的であり、レドックスサイクルによる触媒反応の報告例はほとんどない。今後、Pt(II)/(IV)のレドックスサイクルで進行する新規な合成変換への利用が期待される。

  • 非平面π共役系を有する高次アザヘリセン類の短工程合成とキロプティカル特性の評価

    2020   大谷 卓

     View Summary

    ヘリセンとは非平面縮合多環式芳香族化合物の総称であり、らせん不斉を有することから、そのキロプティカル特性を活かした機能性有機材料としての利用が期待されている。しかし、炭素のみから構成されるカルボヘリセンは、一般に合成に多工程を要し、蛍光量子収率が低いことが課題であった。本研究では、ヘリセン骨格にヘテロ原子として窒素を複数導入したポリアザヘリセンに着目した。その結果、市販試薬から、超原子価ヨウ素を用いる酸化的カップリングを鍵反応として、僅か2〜3工程でポリアザ[5]-[9]ヘリセンの合成を達成した。さらにそれらの光基礎物性を評価したところ、ヘリセン類として比較的高い蛍光量子収率と円偏光発光特性を示した。

  • チオ基を配向基とするカルボヘテロ原子化による高効率分子変換法の開発

    2019   杉山 颯

     View Summary

    炭素−ヘテロ原子結合の開裂を伴うカルボヘテロ原子化は、原子効率100%で炭素−炭素と炭素−ヘテロ原子結合を同時に形成できる理想的な合成変換である。報告者は、配向基としてさらなる合成変換可能なチオ基を用いた反応を総括的に検討しており、既にアルキンのアルキニルチオ化を達成した。今回、チオ基の配向性を利用したアルケニルチオ化、アリールチオ化への展開を行った。その結果、2-メチルチオフェニル基を有するアルケニルスルフィドに対して、カチオン性Rh触媒とジフェニルホスフィン配位子を用いることで、種々の末端アルキンに対するビニルチオ化、アリールチオ化が進行し、合成中間体としてビニルスルフィド類が得られた。

  • 炭素-炭素結合開裂を起点とした新規な多環式芳香族炭化水素の効率合成

    2018  

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    遷移金属錯体による炭素-炭素結合開裂を起点とする反応は、比較的単純な化合物から複雑な炭素骨格を構築できる原子効率が高い合成変換である。炭素-炭素結合活性化の手法として最も汎用されるのが、小員環の環歪みの解消を駆動力とする方法であり、例えば、四員環のシクロブタジエンに2つのベンゼン環が縮環したビフェニレンは、典型的な基質である。本研究では、配向基かつ反応部位としてアルケン部位を有するビフェニレンを用いた分子内反応を検討した。その結果ロジウム触媒を用いることで、所望のより混み合った炭素−炭素結合が開裂し、引き続きアルケンが挿入することで分子内[4+2]付加環化反応が進行することを見出した。

  • 不斉窒素原子を有するジアザトリプチセンの合成と応用

    2017   伊藤 守, 川崎 涼介, 井上 大輔

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    本研究では、堅固な構造を有する三次元骨格として、配位子の母骨格や高分子の基本ユニットとして活用されながら、キラル素子として利用されていなかったトリプチセン骨格に注目する。中でも2つの橋頭位に窒素原子を有する置換ジアザトリプチセンは、窒素原子上に中心不斉を有する過去の合成例がない新規なキラル骨格である。本年度はその予備的な研究として、窒素原子を環内に有する七員環の8π系化合物であるアゼピンに2つのベンゼン環が縮環したジベンザゼピン骨格の効率的な構築を目指した。アゼピンに代表されるヘテロピンは三次元の桶型構造であるため、置換基の導入によりキラリティの導入が可能である。

  • ヘテロ元素を導入した非平面π共役系縮合多環化合物群の創製と評価

    2017   鵜野 仁和, 高野 秀明

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    本研究は、ヘテロ元素を導入した縮合多環π共役系の中で、特に非平面π共役系を有する化合物とその光基礎物性の評価を目的とする。具体的には、環内に一つのヘテロ原子を有する共役七員環骨格であるヘテロピンに、3つベンゼン環が縮環したトリベンゾヘテロピンに注目した。報告者は既に、ロジウム触媒を用いた不斉[2+2+2]付加環化により、硫黄原子を有するトリベンゾチエピンの触媒的不斉合成を達成した。本研究では、イリジウム触媒を用いた脱水素型Si-H/C-Hカップリングを用いることにより、ケイ素を有するトリベンゾシレピンの触媒的合成法を見出した。さらに、構造解析、光学分割による不斉合成、熱的安定性について調査を行った。

  • 炭素-水素結合活性化を伴う触媒的不斉共役付加反応の開発

    2017   栗田 久樹, 小野田 早穂子

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    炭素−水素結合の開裂を起点とする合成変換は、官能基の事前導入が不要であり、その事前導入した官能基に由来する副生成物が生成しないため、原子効率の点で理想的な合成変換である。一方、不活性な炭素−水素結合を開裂するためには、反応点に触媒を近づけるために配向基が重要である。実際に、遷移金属触媒による炭素−水素結合の活性化において配向基の導入により様々な形式の合成変換が報告されている。しかしながら炭素−水素結合活性化を起点とする不斉反応の報告例は未だ少ない。今回報告者は、イリジウム錯体と光学活性ホスフィンから調製される不斉触媒により、高エナンチオ選択的な不斉C-H共役付加反応を達成した。

  • 光学活性ヘテロトリプチセン誘導体の不斉合成と応用

    2016  

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    &nbsp;ヘテロ元素を含んだ縮合多環式化合物が機能性材料として注目されている。中でも中員環を導入した化合物は歪んだ骨格を有し、平面構造を有するアセン類とは異なる新規な物性が期待される。今回我々は、ジフェニルチオエーテルで架橋された1,8-ジインあるいは、2-スルファニルビフェニルで架橋された1,8-ジインとモノアルキンとの[2+2+2]付加環化を検討したところ、キラルなカチオン性ロジウム触媒を用いることで、効率的に反応が進行し、異なる置換形式の多置換トリベンゾチエピン誘導体が高鏡像体過剰率で得られた。本反応では、ヘテロ元素として硫黄に加え、セレンあるいは酸素架橋の1,8-ジインを用いた際にも高鏡像体過剰率で目的の環化体であるトリベンゾヘテロピンが得られた。

  • ヘテロ元素を含む非平面π共役系縮合多環化合物群の創製

    2016  

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     窒素を含む七員環化合物であるアゼピンに2つのベンゼン環が縮環したジベンゾアゼピンは、多くの医薬品の部分骨格として知られている重要な構造である。我々は、原子効率が高い環化異性化に着目し、ジベンゾアゼピン誘導体の合成を試みた。七員環を構築するためには、進行し易い6-exo-dig型環化ではなく、7-endo-dig型環化を選択的に進行させるため、基質の剛直性と高い求核性を期待しカルバゾール骨格を含む基質を反応に用い検討を行った。その結果、金触媒存在下、所望の7-endo-dig型の環化異性化が選択的に進行し、目的の置換ジベンザゼピン誘導体を高収率で得ることができた。

  • 触媒的付加環化反応を利用した大環状ペプチドの効率合成

    2016  

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     環状ペプチドは直鎖ペプチドと比較して標的タンパク質と相互作用しやすく、またタンパク質分解酵素によって分解されにくいなどの特徴を有している。一方我々は、分子内[2+2+2]付加環化反応による分岐型トリインを用いた三脚型シクロファン、およびアミノ酸架橋トリインを用いたアミノインダンカルボン酸誘導体の高エナンチオ選択的合成を達成している。そこで本研究では、分子内[2+2+2]付加環化反応による環状ペプチドの触媒的合成を試みた。その結果、1,6-ジインとアルキン部分がペプチド鎖で架橋されたトリインの分子内[2+2+2]付加環化反応が進行し、種々の環状ペプチドを得ることに成功した。さらに塩基性、酸性アミノ酸を含む環状ペプチドの合成も達成した。

  • 触媒的炭素-水素結合活性化を起点とする非天然アミノ酸の創製と応用

    2014   田原 優樹

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    アミノ酸誘導体は、生命維持機能や生体調節機能に加え、生理活性や医薬品の部分構造に含まれるなど、それらの機能は多岐にわたっている。特に非天然のアミノ酸は医薬品のビルディングブロックとしての利用や、未知なる機能が期待されている。そこで我々は炭素-水素結合活性化を起点とし、キラルな4位置換γ-アミノ酸誘導体の不斉合成を目指した。その結果、カチオン性イリジウム錯体とキラル二座リン配位子から調製される触媒存在下、配向基としてピリジル基を導入したγ-ラクタムと種々のアルケンの反応が進行し、キラルなγ-ラクタム誘導体が得られた。引き続き、水素添加、還元で配向基の除去、加水分解によりキラルな4位置換γ-アミノ酸誘導体を得た。

  • エナンチオ選択的反応を用いた面不斉パラシクロファン配位子の創製

    2013  

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     新規かつ種々の誘導体の合成が容易な不斉配位子群の合成手法の開発は、多彩な不斉炭素骨格の構築に直結する極めて重要な課題である。不斉配位子の不斉要素として、BINAPに代表される軸不斉、SDP、QuinoxP*に代表される中心不斉が挙げられる。一方、「面不斉」リン配位子として、二置換フェロセニル骨格を有する化合物が研究されており、市販の化合物も多い。さらに、面不斉「パラシクロファン骨格」を有する二座配位子としてPHANEPHOS (bis(diphenylphosphino)[2.2]paracyclophane)が市販されているが、BINAP誘導体や二置換フェロセン誘導体と比較して研究が立ち後れている。その理由は、効率的かつ汎用な不斉合成法が少ないのが一因である。 今回我々は、当研究室が開発した不斉オルトリチオ化による面不斉パラシクロファンの高エナンチオ選択的手法により、 [1,n]パラシクロファン骨格を有するモノホスフィン化合物、ならびにジホスフィン化合物を高鏡像体過剰率で不斉合成した。本法により、架橋部の炭素数、構造、あるいはリン上の置換基など、多彩な面不斉リン化合物を得ることが出来る。 さらに、これらの面不斉リン化合物の不斉配位子としての適用として、まず当研究室で開発したパラジウム触媒を用いる連続的不斉Sonogashiraカップリングの不斉配位子として用いた。その結果、これまでに検討した全てのリン化合物よりも高いエナンチオ選択性を達成した(最高90% ee)。また、同様にパラジウム触媒を用いる反応として、Suzukiカップリングを検討した。過去において、中程度のエナンチオ選択性であり、しかも塩基として有毒な水酸化タリウムを用いることが必須であったジクロロフェロセン化合物の非対称化による不斉Suzukiカップリングをモデル反応として検討した結果、通常の無機塩基である炭酸ナトリウムを用い、80% eeを越える高エナンチオ選択的にモノアリール化生成物が得られた。 上記の通り、我々が独自開発した手法により不斉合成したオリジナルなリン化合物の不斉配位子として有効性を実証できた。今後、パラジウム以外の金属触媒の不斉配位子として、さらにはそれ自体を不斉有機触媒として検討する予定である。

  • 光学活性メタラロセン化合物の触媒的不斉合成法の開発と応用

    2012  

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     金属が2つのシクロペンタジエニル基によりサンドウィッチ状に挟まれたメタラロセン化合物の中で、金属が鉄であるフェロセンとその誘導体は、その特徴的な構造と化学的・熱力学的・酸化還元的安定性から様々な分野で応用されている。その代表例が不斉リン配位子であり、例えば、フェロセン骨格を持つキシリホス(xyliphos)は除草剤(S)-Metolachlorの年10000トン以上のスケールでの工業的な不斉合成に用いられており、工業的な利用に耐えうる数少ない不斉リン配位子の一つである。しかしながら、このようなキラルな1,2-二置換フェロセンの合成には、化学量論量の有機金属試薬を用いるジアステレオ選択的な手法が多く用いられていた。一方、当研究室ではこれまでにカチオン性イリジウム、ロジウム触媒を用いて配向性置換基を持つ反応基質の炭素-水素結合活性化反応を利用した炭素-炭素結合生成反応の開発を行った。そこで本研究では、配向性置換基を利用した炭素-水素結合の活性化により、直接的な炭素-炭素結合生成反応によって、フェロセン誘導体の合成およびその不斉合成を目指した。 配向基としてイミノ基を有するフェロセン用い、三価ロジウム触媒存在下、イソシアナートとの反応を試みたところ、イミノ基のα位がアミド化された二置換体フェロセン誘導体が得られた。反応条件の最適化の結果、対アニオンとしてテトラフルオロホウ酸(BF4)を用いることで、電子求引性あるいは供与性置換基を有するフェニルイソシアナート、あるいはアルキルイソシアナートとの反応が進行し、対応する二置換体フェロセン誘導体が得られた。 そこで次に、本系を不斉反応へ展開し、キラルな配向基としてオキサゾリン環を用いて検討を行った。その結果イミノ基を配向基とするフェロセンと同様にアリールイソシアナート、アルキルイソシアナートに対しても反応が進行した。また、いずれの反応においても生成物は単一のジアステレオマーとして得られ、特にパラクロロフェニルイソシアナートとの反応生成物は単結晶であり、X線による結晶構造解析により立体構造を確定できた。 上記のように、カチオン性ロジウム触媒を用いることにより、炭素―水素の直接的な官能基化によるキラル二置換フェロセン化合物の合成を達成した。今後、プロキラルなフェロセン化合物のエナンチオ選択的な不斉合成を目指す。

  • フェニレン系ポリマーの創製を指向した光学活性パラシクロファン素子の不斉合成

    2010  

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     シクロファンとは、広義で芳香族化合物を含む大環状架橋型化合物である。これまで架橋構造により歪みをもつシクロファン類や、多数の環状構造を架橋部に有する複雑な骨格のシクロファン類の合成が達成された。近年では、シクロファン類のもつ機能性に注目が集まり、ホスト-ゲスト化学のゲスト化合物として多くの研究例がある。中でも、ベンゼン環のパラ位の2つの置換基を環構造で連結した化合物をパラシクロファンと言い、架橋鎖が短い場合にはベンゼン環が自由回転できないために、面不斉を生じ鏡像異性体が存在する。これまで既に、パラシクロファン化合物の面性キラリティを利用し、キラル認識剤、キラルポリマー、不斉配位子などとしての応用が報告されているが、それらは光学分割や不斉結晶化などで合成された。一方、パラシクロファン化合物のエナンチオ選択的不斉合成は僅か3例のみであり、しかも不斉収率の最高値は、我々が報告した79% eeであった。 そこで本研究では、ベンゼン環と架橋鎖を酸素原子により連結したヒドロキノン型のパラシクロファンを用い、酸素への配位を利用した不斉オルトリチオ化を検討した。その結果、sec-BuLiとキラルジアミン配位子であるsparteineを作用させたところ、高エナンチオ選択的にモノリチオ化が進行し、キラルなアリールリチウム試薬が得られた。さらに、過剰量のsec-BuLiを加えた場合、パラ位で位置選択的かつ高エナンチオ選択的(99% ee)にジリチオ化が進行し、C2対称を有するキラルなアリールジリチウム試薬が得られた。得られたキラルなモノリチオ化、ジリチオ化体を種々の求電子剤と反応させることにより、種々の長さの架橋鎖、種々の官能基を1つないし2つ有する面不斉パラシクロファンが極めて高不斉収率で得られた。

  • 不斉触媒と反応媒体の機能を兼ね備えた多機能分子の創製

    2009  

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    「環境にやさしい化学 (Green Chemistry)」の達成が求められる今日、従来のように効率的に目的化合物を合成するだけでなく、反応、後処理、精製の全ての過程を通して環境負荷を低減させたシステムの構築が求められている。その対策として、(1) 等量反応から触媒反応へ、(2) 副生成物が少ない反応系の開発、(3) 回収再利用可能な反応媒体(溶媒)の利用、などが挙げられる。本研究では、遷移金属”触媒”を用いる反応において、”副生成物の低減化”を実現するC-H結合活性化反応、ならびに”反応媒体と不斉触媒を兼ね備えた”機能性分子の創製を目指した。 C-H結合の活性化を伴う直接的な変換反応は、従来の官能基を起点とする反応と異なり、反応点への官能基の導入が不要でありことから反応工程数を減ずることができ、さらには反応の進行に伴って生成する官能基に由来した副生成物も低減できる。報告者は、カチオン性イリジウム錯体に注目し、アリールケトンのカルボニル基への配位により、そのオルトのsp2C&#8211;H結合活性化を起点する種々の触媒反応を開発した。すなわち、アリールケトンのアルケニル化、さらには引き続く環化反応によりベンゾフルベンの合成を達成した。また、分子内に求核付加を受ける別のカルボニル基を導入することで、分子内環化反応が進行し、4-置換ベンゾヘテロールの合成を達成し、またアミドに隣接したsp3C&#8211;H結合のアルケニル化も達成した。 一方、反応媒体に不斉触媒能を付与する試みとして、報告者が開発したイリジウム触媒によるエン型反応において、イリジウム錯体の対アニオンとして天然物由来の安価な不斉源を検討した。すなわち、反応媒体としてイオン性液体への展開を視野に入れ、種々のアミノ酸塩を検討したが、反応は進行するものの、不斉誘起されなかった。

  • メタラサイクルを活性中間体とする多官能性環状化合物の触媒的合成

    2006  

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     報告者は既に、キラルイリジウム触媒を用いる対称ジインと対称モノアルキンとのエナンチオ選択的分子間[2+2+2]付加環化反応を報告した。本反応は、軸不斉をもつC2対称キラルテルアリール化合物を高収率かつ極めて高い不斉収率で与える。これまでに報告したジインのカップリングパートナーは、両プロパルギル位に酸素官能基を有するアルキンのみであった。そこで本研究で一つあるいは二つの官能基をもつ種々のモノアルキンの検討、さらには炭素-炭素多重結合に替え、炭素-ヘテロ元素多重結合をもつ化合物を検討した。 まずプロパルギル位に、一つの水酸基、アミノ基、ホスフィニル基を有するアルキンとジインとの反応を行った結果、いずれの場合も環化生成物であるテルアリール化合物が、単一ジアステレオマー、かつほぼ一方の鏡像異性体のみで得られた。さらに、アミノ基と水酸基をともに有するアルキンでも反応が進行し、ほぼ光学的純粋なアミノアルコールが得られた。これらの結果は、エナンチオ選択的[2+2+2]付加環化反応により種々の官能性基を有する軸不斉化合物が得られるたこと意味する。 次に、ジカルボニル化合物とジインの反応を検討した結果、ロジウム錯体を用いることにより、ヘテロ[2+2+2]付加環化反応が進行することを見いだした。1,6-ジインとピルビン酸エステルの反応では、環化体として二環性2H-ピラン化合物の生成を確認できたが、単離精製する過程で不安定な2H-ピラン環が開環し、ジエノン体として得られた。不斉反応へ展開するため1,7-ジインを用いたところ、二環性2H-ピラン化合物を単離同定することができた。現在のところ中程度(50% ee)の不斉収率を達成できたが、今後エナンチオ選択性を向上させ、不斉ヘテロ[2+2+2]付加環化反応による不斉炭素を有する複素環化合物の合成を目指す。

  • 無溶媒反応を指向した多機能型高分子不斉触媒の創製

    2004  

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    「環境にやさしい化学 (Green Chemistry)」の理論化と実践が求められる今日、反応媒体として基質に対し大量に用いられる有機溶媒が大きな問題となっている。本研究は、不斉触媒と反応媒体の2つの機能を兼ね備えた高分子触媒の創製が最終目標である。溶媒を用いないことで、生成物と触媒の分離精製が容易になるだけでなく、触媒の再利用が可能であり、環境負荷が小さく、かつ経済効率の高い不斉触媒システムの構築が可能となる。 本年度は、予備的実験として、近年注目されている新反応媒体の一つである有機イオン性液体中での触媒反応を検討した。有機イオン性液体は、(1) 大きな装置が不要、(2) 安価かつ取扱いが容易、(3) 目的に合わせて違う骨格をもつ物質の合成が可能、などの利点をもつ。 その結果、イリジウム触媒を用いる1,6-エンインの環化異性化反応が、通常用いる有機溶媒であるトルエン中より、有機イオン性液体であるイミダゾリウム塩中で加速され、高効率的に生成物を与え、また反応媒体の再利用も可能であることを見いだした。これまで、水素化反応、カップリングなどの遷移金属錯体を用いる触媒反応で、イオン性液体が利用された例は知られているが、環化異性化反応では初めての例である。 現在、無溶媒化反応へのステップとして、イリジウム錯体のイミダゾリウム塩への担持、さらには不斉反応への検討を行っている。

  • 環境負荷を考慮した光学活性環状化合物合成法の開発

    2003  

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    「環境にやさしい化学 (Green Chemistry)」を達成する上で、反応媒体として基質に対し大量に用いられる有機溶媒が大きな問題となっている。一方不斉触媒反応では、立体選択性(不斉収率)、反応効率(TOF)、触媒活性(TON)などの点で実用性の高い反応系を構築するために、溶媒選択は極めて重要なファクターである。本研究は、新たな反応媒体の探索という従来のアプローチではなく、反応媒体を必要としない無溶媒型触媒システムの開発、特に不斉触媒系に焦点をあて、研究を行った。 その結果報告者は、Pauson-Khand型反応で無溶媒型不斉触媒反応を見いだした。Pauson-Khand型反応は、一酸化炭素挿入を伴うアルケン-アルキンカップリング反応であり、シクロペンテノン骨格を構築する有用な反応のひとつである。従来の不斉Pauson-Khand型反応は、有機溶媒を用い、一酸化炭素源としてCOガスを用いており、報告者も、同条件下、キラルイリジウム錯体により、高エナンチオ選択的な反応を既に発表している。そこで、遷移金属錯体によるカルボニル化合物の脱カルボニル化反応に着目し、アルデヒドのカルボニル部位を一酸化炭素源として活用する触媒系を検討した。その結果、無溶媒条件下、a,b-不飽和アルデヒドであるシンナムアルデヒドを用い、光学活性ロジウム触媒を用いることで、高エナンチオ選択的な不斉カルボニル化反応が進行し、高い鏡像体過剰率のシクロペンテノン誘導体が得られた。 従来、遷移金属錯体を用いる反応では、触媒サイクルを効率的に回すために、反応溶媒の使用が必要とされてきた。本研究により、反応系の巧みな設計が無溶媒系の構築を可能にすることがわかったことから、遷移金属触媒を用いる他の有用な合成反応における無溶媒系の設計を目指す。

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