Takeshi Ohkuma

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPractical Enantioselective Hydrogenation of Aromatic KetonesTakeshi Ohkuma, Hirohito Ooka, Shohei Hashiguchi, Takao Ikariya, and Ryoji NoyoriCite this: J. Am. Chem. Soc. 1995, 117, 9, 2675–2676Publication Date (Print):March 1, 1995Publication History Published online1 May 2002Published inissue 1 March 1995https://pubs.acs.org/doi/10.1021/ja00114a043https://doi.org/10.1021/ja00114a043research-articleACS PublicationsRequest reuse permissionsArticle Views

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTAsymmetric Hydrogenation of Alkenyl, Cyclopropyl, and Aryl Ketones. RuCl2(xylbinap)(1,2-diamine) as a Precatalyst Exhibiting a Wide ScopeTakeshi Ohkuma, Masatoshi Koizumi, Henri Doucet, Trang Pham, Masami Kozawa, Kunihiko Murata, Eiji Katayama, Tohru Yokozawa, Takao Ikariya, and Ryoji NoyoriView Author Information Department of Chemistry and Research Center for Materials Science, Nagoya University Chikusa, Nagoya 464-8602, Japan ERATO Molecular C

ADVERTISEMENT RETURN TO ISSUEPREVArticlePreferential hydrogenation of aldehydes and ketones.Takeshi Ohkuma, Hirohito Ooka, Takao Ikariya, and Ryoji NoyoriCite this: J. Am. Chem. Soc. 1995, 117, 41, 10417–10418Publication Date (Print):October 1, 1995Publication History Published online1 May 2002Published inissue 1 October 1995https://doi.org/10.1021/ja00146a041RIGHTS & PERMISSIONSArticle Views4678Altmetric-Citations321LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full te

Chiral eta6-arene/N-tosylethylenediamine-Ru(II) complexes, known as excellent catalysts for asymmetric transfer hydrogenation of aromatic ketones in basic 2-propanol, can be used for asymmetric hydrogenation using H2 gas. Active catalysts are generated from RuCl[(S,S)-TsNCH(C6H5)CH(C6H5)NH2](eta6-p-cymene) in methanol, but not 2-propanol, or by combination of Ru[(S,S)-TsNCH(C6H5)CH(C6H5)NH](eta6-p-cymene) and CF3SO3H or other non-nucleophilic acids. This method allows, for the first time, asymme

Reaction of a chiral RuCl2(diphosphine)(1,2-diamine) complex and NaBH4 forms trans-RuH(eta1-BH4)(diphosphine)(1,2-diamine) quantitatively. The TolBINAP/DPEN Ru complex has been characterized by single crystal X-ray analysis as well as NMR and IR spectra. The new Ru complexes allow for asymmetric hydrogenation of simple ketones in 2-propanol without an additional strong base. Various base-sensitive ketones are convertible to chiral alcohols in a high enantiomeric purity with a substrate/catalyst

This chapter contains sections titled: Introduction Chiral Ligands Hydrogenation of Olefins Hydrogenation of Ketones Hydrogenation of Imines Conclusion References

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTAsymmetric Hydrogenation of Amino Ketones Using Chiral RuCl2(diphophine)(1,2-diamine) ComplexesTakeshi Ohkuma, Dai Ishii, Hiroshi Takeno, and Ryoji NoyoriView Author Information Department of Chemistry and Research Center for Materials Science Nagoya University, Chikusa, Nagoya 464-8602, Japan Cite this: J. Am. Chem. Soc. 2000, 122, 27, 6510–6511Publication Date (Web):June 24, 2000Publication History Received29 March 2000Published online24 June 2

A combined system of RuCl2(tolbinap)(pica) and an alkaline or organic phosphazene base catalyzes asymmetric hydrogenation of sterically congested tert-alkyl ketones (TolBINAP = 2,2'-bis(di-4-tolylphosphino)-1,1'-binaphthyl, PICA = alpha-picolylamine). Hydrogenation with RuH(eta1-BH4)(tolbinap)(pica) does not require any strong base. Alcoholic solvents strongly affect the catalytic efficiency. The reaction proceeds smoothly in ethanol under 1-20 atm of H2 and at room temperature with a substrate

[reaction: see text] trans-RuCl2[P(C6H4-4-CH3)3]2(NH2CH2CH2NH2) acts as a highly effective precatalyst for the hydrogenation of a variety of benzophenone derivatives to benzhydrols that proceeds smoothly at 8 atm and 23-35 degrees C in 2-propanol containing t-C4H9OK with a substrate/catalyst ratio of 2000-20000. Use of a BINAP/chiral diamine Ru complex effects asymmetric hydrogenation of various ortho-substituted benzophenones and benzoylferrocene to chiral diarylmethanols with consistently high

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTAsymmetric Activation of Racemic Ruthenium(II) Complexes for Enantioselective HydrogenationTakeshi Ohkuma, Henri Doucet, Trang Pham, Koichi Mikami, Toshinobu Korenaga, Masahiro Terada, and Ryoji NoyoriView Author Information Department of Chemistry and Molecular Chirality Research Unit, Nagoya University, Chikusa, Nagoya 464-8602, Japan Department of Chemical Technology, Tokyo Institute of Technology, Meguro, Tokyo 152, Japan Cite this: J. Am. Ch

trans-RuCl(2)[(R)-xylbinap][(R)-daipen] or the S,S complex acts as an efficient catalyst for asymmetric hydrogenation of hetero-aromatic ketones. The hydrogenation proceeds with a substrate-to-catalyst molar ratio of 1000-40000 to give chiral alcohols in high ee and high yield. The enantioselectivity appears to be little affected by the properties of the hetero-aromatic ring. This method allows for asymmetric synthesis of duloxetine, an inhibitor of serotonin and norepinephrine uptake carriers.

Asymmetric hydrogenation of various alpha-chloro aromatic ketones with Ru(OTf)(TsDPEN)(eta6-arene) (TsDPEN = N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine) produces the chiral chlorohydrins in up to 98% ee. This reaction can be conducted even on a 206-g scale. The hydrogenation of an alpha-chloro ketone with a phenol moiety has been utilized for the synthesis of (R)-norphenylephrine without protection-deprotection operations. [reaction: see text].

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTStereoselective Hydrogenation of Simple Ketones Catalyzed by Ruthenium(II) ComplexesTakeshi Ohkuma, Hirohito Ooka, Masashi Yamakawa, Takao Ikariya, and Ryoji NoyoriView Author Information ERATO Molecular Catalysis Project, Research Development Corporation of Japan, 1247 Yachigusa, Yakusa-cho, Toyota 470-03, Japan Cite this: J. Org. Chem. 1996, 61, 15, 4872–4873Publication Date (Web):July 26, 1996Publication History Received29 May 1996Published on

Asymmetric hydrogenation of a series of alpha-hydroxy aromatic ketones in methanol catalyzed by Cp*Ir(OTf)(MsDPEN) (MsDPEN = N-(methanesulfonyl)-1,2-diphenylethylenediamine) affords the 1-aryl-1,2-ethanediols in up to 99% ee. The reaction can be conducted with a substrate-to-catalyst molar ratio as high as 6000 under 10 atm of H2. 1-hydroxy-2-propanone is also hydrogenated with high enantioselectivity.