Yoshiaki Nishibayashi

Recent advances in the transition-metal-catalyzed enantioselective propargylic substitution reactions of propargylic alcohol derivatives with nucleophiles are reviewed in this article. After the disclosure of the first example of a ruthenium-catalyzed propargylic alkylation, various types of enantioselective propargylic substitution reactions, including enantioselective propargylation of aromatic compounds, have been reported in the last eight years. In addition, a variety of enantioselective pr

This paper describes our recent progress in catalytic nitrogen fixation by using transition-metal-dinitrogen complexes as catalysts. Two reaction systems for the catalytic transformation of molecular dinitrogen into ammonia and its equivalent such as silylamine under ambient reaction conditions have been achieved by the molybdenum-, iron-, and cobalt-dinitrogen complexes as catalysts. Many new findings presented here may provide new access to the development of economical nitrogen fixation in pl

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTNovel Propargylic Substitution Reactions Catalyzed by Thiolate-Bridged Diruthenium Complexes via Allenylidene IntermediatesYoshiaki Nishibayashi, Issei Wakiji, and Masanobu HidaiView Author Information Department of Chemistry and Biotechnology Graduate School of Engineering, The University of Tokyo Hongo, Bunkyo-ku, Tokyo 113-8656, Japan Cite this: J. Am. Chem. Soc. 2000, 122, 44, 11019–11020Publication Date (Web):October 21, 2000Publication Hist

Highly diastereoselective ortho-lithiation (84-99% de) of chiral oxazolinylferrocenes followed by quenching with an electrophile such as MeI, PPh2Cl or (PhSe)2 leading to the corresponding ortho-substituted ferrocenes is accomplished. The molecular structure of a phenylseleno-substituted compound, fully characterized by X-ray crystallography, showed the attack of the electrophile from the unexpected site.

Treatment of the tungsten dinitrogen complex cis-[W(N2)2(PMe2Ph)4] (Me = methyl, Ph = phenyl) with an equilibrium mixture of [RuCl(dppp)2]X and trans-[RuCl(eta2-H2)(dppp)2]X [X = BF4, PF6, or OSO2CF3; dppp = 1,3-bis(diphenylphosphino)propane] under 1 atmosphere of dihydrogen at 55 degrees Celsius for 24 hours gave NH3 in moderate yield. The same reaction in the presence of acetone produced acetone azine in high yield. None of these reactions proceeded in the absence of dihydrogen.

A combination of nickel and photoredox catalysts promoted novel cross-coupling reactions of aryl halides with 4-alkyl-1,4-dihydropyridines. 4-Alkyl-1,4-dihydropyridines act as formal nucleophilic alkylation reagents through a photoredox-catalyzed carbon-carbon (C-C) bond-cleavage process. The present strategy provides an alternative to classical carbon-centered nucleophiles, such as organometallic reagents.

The scope and limitations of the ruthenium-catalyzed propargylic substitution reaction of propargylic alcohols with heteroatom-centered nucleophiles are presented. Oxygen-, nitrogen-, and phosphorus-centered nucleophiles such as alcohols, amines, amides, and phosphine oxide are available for this catalytic reaction. Only the thiolate-bridged diruthenium complexes can work as catalysts for this reaction. Results of some stoichiometric and catalytic reactions indicate that the catalytic propargyli

Two cats. in the same pot: The two catalysts [Cp*RuCl(μ2-SMe)2RuCp*Cl] (1) and PtCl2 (2) promote a sequence of catalytic cycles in the same medium. Tri- or tetrasubstituted furans or pyrroles are afforded in moderate to good yields with high regioselectivities from the catalyzed reactions of propargylic alcohols with ketones or with ketones and anilines, respectively (see scheme; cats.=catalysts).

Ruthenium complexes with (oxazolinylferrocenyl)phosphines, RuCl2(PPh3)((oxazolinylferrocenyl)phosphine), have been prepared and characterized by spectroscopy. These ruthenium complexes are very effective catalysts for asymmetric hydrosilylation of not only ketones but also an imine to give the corresponding sec-alcohols (up to 97% ee) and a sec-amine (88% ee) after acid hydrolysis, respectively.

Copper-catalyzed enantioselective propargylation of indoles with propargylic esters and sequential Huisgen cycloaddition with azides lead to the construction of chiral triarylmethanes, bearing a quaternary carbon center, with high to excellent enantioselectivities. The result described herein can be used in the enantioselective preparation of a tetraarylmethane.

A novel ruthenium-catalyzed propargylation of aromatic compounds with propargylic alcohols has been found to afford the corresponding propargylated aromatic products in good yields with complete regioselectivity. The catalytic reaction provides a potential usefulness for practical application in organic synthesis, because the selective propargylation of aromatic compounds with an aromatic C-H bond cleavage is generally difficult.

N2 is fixed as NH3 industrially by the Haber-Bosch process under harsh conditions, whereas biological nitrogen fixation is achieved under ambient conditions, which has prompted development of alternative methods to fix N2 catalyzed by transition metal molecular complexes. Since the early 21st century, catalytic conversion of N2 into NH3 under ambient conditions has been achieved by using molecular catalysts, and now H2O has been utilized as a proton source with turnover frequencies reaching the

The ruthenium complex RuCl2(PPh3)(oxazolinylferrocenylphosphine), 1, has been found to be a quite effective catalyst for asymmetric transfer hydrogenation of not only alkyl aryl ketones but also alkyl methyl ketones with iPrOH. Asymmetric oxidation of racemic sec-alcohols with acetone via kinetic resolution by using the same catalyst 1 also proceeds with exteremely high enantioselectivity (>99.9% ee).

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChiral Oxazolinylferrocene-Phosphine Hybrid Ligand for the Asymmetric Hydrosilylation of KetonesYoshiaki Nishibayashi, Kyohei Segawa, Kouichi Ohe, and Sakae UemuraCite this: Organometallics 1995, 14, 12, 5486–5487Publication Date (Print):December 1, 1995Publication History Published online1 May 2002Published inissue 1 December 1995https://doi.org/10.1021/om00012a012Request reuse permissionsArticle Views766Altmetric-Citations139LEARN ABOUT THESE METRICS