We describe an Ir-catalyzed intramolecular reaction of 2-alkynyl diaryl sulfides, which gives 9-arylidene-9H-thioxanthene derivatives via 6-exo-dig cyclization. When 2-alkynylphenyl naphthyl sulfides are used, divergent synthesis of triaryl-fused thiepines and diaryl-substituted benzothiophenes can be achieved by simply choosing the reaction temperature. (Figure presented.).

This study elucidates that relativistic effect plays a key role in catalytic C-H activation using a cationic Ir complex. Experiments show that the cationic Ir(I)-diphosphine catalyst can be used for the deuterium substitution of N-phenylbenzamide, whereas a cationic Rh(I)-diphosphine catalyst is scarcely effective. Density functional theory calculations, including the relativistic effect, demonstrate a large difference in the reaction energy diagrams for the C-H activation of N-phenylbenzamide between the cationic Ir and Rh catalysts. In particular, the relatively low reaction barrier and considerably stabilized product obtained for the Ir catalysts are rationalized by strong Ir-C and Ir-H interactions, which originate from the relativistic self-consistent d-orbital expansion of Ir.

Truxene is a C3-symmetric compound with characteristic photophysical properties, and it has great potential as a light-emitting material and building block. In this study, we demonstrate the synthesis of hexaazatruxenes using a two-step protocol. First, the hexaazatruxene precursors were prepared through the Buchwald-Hartwig amination of 1,3,5-tribromobenzene with commercially available or easily prepared amino-pyridine derivatives. Then, hexaazatruxenes were synthesized through consecutive N−H/C−H coupling using a hypervalent iodine reagent. To the best of our knowledge, this is the first report on the synthesis of truxenes containing more than three heteroatoms in the main skeleton.

This chapter describes transition metal-catalyzed protocols for the enantioselective synthesis of planar-chiral and helically chiral compounds. Regarding the generation of planar chirality, asymmetric synthesis of disubstituted ferrocenes is mainly focused, where C-H activation is a straightforward strategy. On the other hand, cyclophanes and helicenes are representative helically chiral compounds. [2+2+2] Cycloaddition and cycloisomerization of alkynes are shown as efficient approach to the creation of helical chirality.

We describe a cationic Ir-catalyzed tail-to-tail dimerization of aryl acrylates starting from vinylic sp2 C−H activation, which gives industrially useful adipic acid ester derivatives in high yields. We further expanded the reaction to an enantioselective dimerization using aryl methacrylates and achieved the first example of catalytic asymmetric dimerization of acrylate derivatives. (Figure presented.).

Oxidation of benzylic sp3 C-H bonds smoothly proceeded at ambient temperature under blue LED (465 nm) photo-irradiation using sulfur-containing tetracyclic compounds as photocatalysts. The use of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as a cosolvent was the key to success: various toluene derivatives were selectively oxidized to substituted benzaldehydes without overoxidation. Preliminary mechanism studies were undertaken, including electron spin resonance (ESR) spectroscopy analyses.

We describe the divergent construction of two nitrogen-containing polycyclic systems by gold-catalyzed cycloisomerizations. The gold-catalyzed cascade hydroamination and 7-endo-dig-selective cycloisomerization of nitrogen-tethered 1,8-diynes yielded indolo[1,7-ab]benzazepines in one pot. In contrast, when Johnphos-coordinated gold catalyst was used, the same 1,8-diynes were transformed into indolo[1,2-a]quinolines by 6-endo-dig-selective cycloisomerization along with rearrangement of the substituent on one of the alkynes. The reaction of a naphthalene-tethered substrate provided a helically chiral aza[6]helicene.

An Ir-catalyzed reaction of N-benzylideneanilines with functionalized alkenes such as α,β-unsaturated esters gave ortho-substituted benzaldehyde derivatives with a functional group at the remote position after acidic treatment. The present transformation involves deconjugative long-range isomerization (chain-walking) up to 11 times and C-H activation using an imino group as a transient directing group.

We designed and synthesized a new series of NHCs with a sulfoxide moiety as a hemilabile ligand. We investigated the catalytic activities of Au(I)-NHC complexes in the strong oxidant-free cross-coupling of iodoarenes with 1, 3, 5-trimeth-oxybenzene. We ascertained that the sulfoxide moiety is critical for the Au(I)/(III) catalytic cycle.

The chiral Ir(I)-catalyzed intermolecular reaction of N-carbamoylpyrrole and indole derivatives with α,β-unsaturated carbonyl compounds such as crotonates proceeded with high enantioselectivity. The obtained chirally functionalized pyrroles and indoles are formal C-H conjugate adducts. The reaction mechanism was studied by deuterium labeling experiments.

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.

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.

The Pd(II)-catalyzed sp 3C-H bond benzoxylation of N -phthaloylalanine derivatives possessing an 8-aminoquinolyl group as a directing group with aldehydes under ambient conditions is reported. When a solution of an alanine derivative and an aldehyde in a toluene/water co-solvent was reacted in the presence of palladium catalyst and tert -butyl hydroperoxide at room temperature, a benzoxylated product was formed in up to 68% yield. The protecting group of the obtained benzoxylated product was smoothly removed to afford a free amide in high yield.

Transition-metal-catalyzed C - C bond activation is one of the most fascinating reactions to construct new C - C bonds because it can convert a simple carbon skeleton directly to a highly complicated carbon framework. In particular, transformations of biphenylene via C - C bond activation are well-known for the synthesis of polycyclic hydrocarbons such as phenanthrene and tetraphenylene. Since the products derived from biphenylene were still limited, there was room for investigation of biphenylene chemistry. Herein we summarize our recent progress for the new reactions of biphenylene by transition-metal catalysts to synthesize various polycyclic hydro¬ carbons. We achieved an iridium-catalyzed intermolecular [4+1] cycloaddition of biphenylenes with alkenes to give 9,9-disubstituted fluorene derivatives and we conducted a mechanism study by DFT calculations. In addition, we developed a new strategy to cleave the sterically hindered C - C bond of biphenylene by using an alkene and an alkyne moiety, respectively, which were used as both a directing group and a reaction site. As a result, dihydrobenzofluoranthene and axially chiral benzofluoranthene derivatives were obtained, which have unique photophysical properties. Furthermore, we achieved skeletal rearrangement via the cleavage of two different C- C bonds by a gold catalyst at ambient temperature and we elucidated reactivity and regioselectivity by experi¬ mental and computational studies.

A method for the synthesis of dihydrodibenzo[c,e]azocine derivatives via a regioselective intramolecular aminoiodination of alkynes under visible light irradiation has been developed. This protocol uses a combination of iodine and hypervalent iodine to realize a sulfonamidyl radical, followed by intramolecular addition to alkyne to form a vinyl radical. Subsequent trapping of iodine radical affords an 8-membered heterocycle. Applications of the obtained iodinated 8-membered heterocycles in the Suzuki-Miyaura coupling and deiodination are also demonstrated. (Figure presented.).

The 7-exo- and 8-endo-dig-selective gold-catalyzed cycloisomerizations of 2-propargylamino biphenyl derivatives were developed. The reaction of terminal alkynes gave dibenzo[b,d]azepines by 7-exo-dig cycloisomerization. In contrast, when internal alkynes were subjected to the reaction, 8-endo-dig cycloisomerization proceeded to provide dibenzo[b,d]azocines. The nucleophilicity at the reaction site and the electron-withdrawing effect of a tosyl group were important for the present selective transformation. This protocol could be used for ynamide substrates and a silver-catalyzed reaction gave 7-exo-dig products selectively.

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.

We describe a simple and practical protocol for the synthesis of benzyl sulfones using readily available toluene derivatives and α-amino acid sulfonamides. The reaction proceeds to afford a broad range of benzyl sulfones in moderate to high yields under silver catalysis. The mechanism possibly involves a Minisci-type formation of α-aminoalkyl radical, homolytic cleavage of a N-S bond to generate a sulfonyl radical, and coupling of sulfonyl radical with a benzyl radical formed via hydrogen abstraction by sulfate anion radical. The practicality of the present reaction is demonstrated by a gram-scale synthesis and one-step synthesis of anticancer-active compound. The mechanism studies are conducted using radical scavengers and deuterated toluene.

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...

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.

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).

– The cationic gold(I)-catalyzed 10-endo-dig-selective cycloisomerization of N-(2-anilinobenzyl)propargylamine derivatives was developed. The reaction proceeded smoothly under mild conditions to give dibenzodiazecines. The catalytic construction of an entropically and enthalpically disfavored ten-membered ring was achieved by using a highly nucleophilic 3,5-dimethoxyanilino group as a reaction site.

<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>

Enantioselective synthesis of azepine-fused planar-chiral ferrocenes was achieved by the chiral cationic Pt-catalyzed intramolecular cycloisomerization of N-propargyl-2-ferrocenylanilines. A mechanistic study using an N-allenyl analogue indicated that the reaction proceeded selectively in a 7-exo-dig manner along with isomerization of the exo-olefin moiety. A methanesulfonylamino tether was crucial for selective cycloisomerization. This is the first example of the enantioselective synthesis of heteropin-fused planar-chiral ferrocenes.

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.

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.

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.

Rh-catalyzed enantioselective intramolecular reactions of triynes consisting of 1,6-diyne and 1,10-diyne moieties tethered by sulfur or oxygen and ortho-phenylene moieties proceeded to give chiral tetrabenzoheteronines possessing a nine-membered ring system as [2+2+2] cycloadducts. In the reaction of triynes consisting of 1,6-diyne and 1,11-diyne moieties, sulfur-tethered substrates gave chiral metacyclophanes with an eleven-membered ring system, whereas an oxygen- and sulfur-tethered substrate afforded a tetrabenzo-1,4-oxathiecine with a ten-membered ring system. The mechanisms of the different reaction pathways depending on the heteroatom of the tether are discussed.

Biphenylene is an antiaromatic compound that has a strained butadiene skeleton that joins two benzene rings. Various methods for synthesizing the biphenylene core have been developed. In addition, the reactivity of biphenylene has attracted much attention because C–C bonds of biphenylene can be cleaved by various organometallic species. Furthermore, the biphenylene motif not only acts as a spacer in a variety of functional molecules, but also serves as a backbone for catalysts and ligands. This minireview summarizes how to construct the biphenylene structure, how to react biphenylene, and how to use the biphenylene skeleton in functional materials.

Cyclic polyarylene is a series of compounds, where the cyclic structure is constructed by a number of phenylene and/or heteroarylene moieties. Cyclic polyarylenes consisting of more than three arylene moieties are non-planar, and introduction of substituent (s) induces axial chirality. We comprehensively studied catalytic and enantioselective synthesis of various cyclic polyphenylenes by consecutive inter- and intramolecular cycloadditions of triynes, where 1,6-diyne and alkyne moieties were tethered by phenylene moiety. We further used this strategy for the construction of cyclic heteroarylenes using thiophene-tethered triynes. Next, we focused on the enantioselective construction of sulfur-containing benzo-fused medium ring systems. For examples, intermolecular cycloaddition of 1,8-diynes tethered by sulfur and two ortho-phenylene moieties with an alkyne gave axially chiral poly-substituted tribenzothiepins possessing a seven-membered ring core. We succeeded in the enantioselective synthesis of seven to eleven-membered benzo-fused compounds by intramolecular reaction of triynes consisting of sulfur-tethered 1,6-diyne and 1, «-diyne moieties (n = 8—11).

Cationic Au(I)-catalyzed intramolecular cycloisomerization of N-(2-alkynylphenyl)indoles proceeded efficiently in exo-selective manner, and (Z)-10-(arylidene)indolo[1,2-a]indole derivatives were obtained in moderate to high yields. Their photophysical properties were also measured.

This chapter focuses on Rh(I)-catalyzed synthetic transformations initiated by carbon-hydrogen (C-H) bond cleavage. The Ru-catalyzed carbonyl-directed C-H alkylation by alkenes is a monumental achievement in organic chemistry. In this reaction, a nitrogen-containing moiety was commonly used as an efficient directing group. Alkynes are conventional coupling partners in C-H activation and alkenylated products are obtained with perfect atom economy. C-H bond cleavage along with carbon-carbon bond-forming reactions provides synthetically useful compounds in one pot. While the metalation of organohalides and subsequent reaction with trialkyl borate is a conventional protocol for the preparation of organoboron compounds, C-H borylation is a more direct and atom-economical approach. Aryl and alkyl silanes are synthetically important because they are functional molecules in themselves and are useful intermediates for further transformations. Among the various approaches to the synthesis of silane-containing compounds, dehydrogenative C-H/Si-H coupling is an atom-economical protocol.

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.

We developed a silver-catalyzed strategy for the generation of sulfonyl radicals from sulfonamides derived from α-amino acids. The reaction proceeded via a decarboxylation, N–S bond cleavage and radical cyclization sequence and allows the difunctionalization of alkynes and the synthesis of 3-sulfonylated coumarins. The reaction tolerated a broad scope of substrates and functional groups and could be extended to the synthesis of oxindoles and an isoquinolinedione by the capturing of the sulfonyl radical with an alkene moiety. Moreover, the proposed mechanism was supported experimentally and by DFT calculations.

The Rh-catalyzed intramolecular reaction of 1-(2-vinylaryl)-substituted biphenylenes was used to construct a dihydrobenzo[b]fluoranthene skeleton. This transformation was achieved by regioselective C−C bond cleavage of a sterically more hindered biphenylene site by using alkene as both a directing group and a reaction moiety. Furthermore, we measured and analyzed the photophysical properties of the new multicyclic fused compounds.

© 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.

© 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.

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.

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.

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.

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.

Recently, we reported an Ir-catalyzed formal [4 + 1] cycloaddition of biphenylenes with alkenes, which gave 9,9-disubstituted fluorenes in moderate to excellent yields. We proposed a reaction mechanism that involved the intermolecular insertion of alkenes, β-elimination, and intramolecular insertion based on the results of experimental mechanistic studies. Herein, we further support the proposed mechanism by density functional theory calculations and explain why [4 + 1] cycloaddition proceeds rather than conventional [4 + 2] cycloaddition.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

[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.

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.

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.

[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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

(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.

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.

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.

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

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.

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.

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.

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.

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.

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.

(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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

(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.

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.

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.

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.

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.

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.

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.

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.

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.

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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.

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.

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.

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.

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.

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.

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.

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.

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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.

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.

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.

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.

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.

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.

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.

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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.

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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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.

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.

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.

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.

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.

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.

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.

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.

An asymmetric [2+2+2] cycloaddition of an α,ω-diyne, possessing ortho-substituted aryl groups on its terminus, and a monoalkyne with oxygen functionalities gave various axially chiral teraryl compounds. The coupling proceeded with extremely high enantio- (>99.5% ee) and diastereoselectivities (dl/meso = >95/5) when catalyzed by an iridium-chiral phosphine complex. As the products were readily transformed into diol compounds by deprotection without racemization, the present procedure provides access to a new chiral pool of diol compounds with C2 symmetry. Copyright © 2004 American Chemical Society.

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.

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.

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.

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.

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.

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.

"Single-handedly", in every sense of the word, the alkylation product shown catalyzes its own asymmetric formation from the corresponding aldehyde. In this way the miniscule initial enantiomeric excess of about 0.00005% was amplified to >99.5% ee after three cycles.

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.

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.

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.

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.

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.

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.

This paper reports a new method for the generation of chiral Lewis superacids by protonation of a non-Lewis acidic oxazaborolidine (1) with triflic acid. The resulting cationic species (3) are powerful and highly enantioselective catalysts for the Diels-Alder reaction of various 1,3-dienes with α,β-enals. An optimization study (see Table 1) led to the selection of reaction conditions and catalysts (6A and 6B) which are very effective. The reactions are simple to conduct, reproducible, and economical, since only ca. 6 mol% of catalyst is required. In addition, the chiral catalyst precursor is readily recovered for reuse (>95% efficiency) and is commercially available. The broad scope of the process is documented by the 14 examples listed in Table 2. The absolute stereochemical course of the Diels-Alder reactions catalyzed by 6A and 6B was successfully predicted on the basis of the mechanistic principles which have recently been formulated for this type of catalytic enantioselective reaction involving re-face attack by the diene on complex 7. The mode of generation of Lewis superacids 6A and 6B allows an approximate comparison (or scale) connecting the catalytic power Lewis and protic acids. Copyright © 2002 American Chemical Society.

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.

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.

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.

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.

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 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.

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.

Helicenes without any heteroatoms have been shown for the first time to act as chiral inducers in the highly enantioselective addition of diisopropylzinc to an aldehyde (see scheme).

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.

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.

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.

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.

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.

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.

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.

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.

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.

(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 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.

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.

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.

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).

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.

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 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.

(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.

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.

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.

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.

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.

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

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

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

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

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.

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%).

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.

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.

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.

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.

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.