title: Chloride-Bridged Dinuclear Rhodium(III) Complexes Bearing Chiral Diphosphine Ligands: Catalyst Precursors for Asymmetric Hydrogenation of Simple Olefins.
abstract: Efficient rhodium(III) catalysts were developed for asymmetric hydrogenation of simple olefins. A new series of chloride-bridged dinuclear rhodium(III) complexes 1 were synthesized from the rhodium(I) precursor [RhCl(cod)]2 , chiral diphosphine ligands, and hydrochloric acid. Complexes from the series acted as efficient catalysts for asymmetric hydrogenation of (E)-prop-1-ene-1,2-diyldibenzene and its derivatives without any directing groups, in sharp contrast to widely used rhodium(I) catalytic systems that require a directing group for high enantioselectivity. The catalytic system was applied to asymmetric hydrogenation of allylic alcohols, alkenylboranes, and unsaturated cyclic sulfones. Control experiments support the superiority of dinuclear rhodium(III) complexes 1 over typical rhodium(I) catalytic systems.
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Toyonaka, Osaka, 560-8521, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kita
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Toyonaka, Osaka, 560-8521, Japan.
authors.forename: Shoji
authors.initials: S
authors.lastname: Hida
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Toyonaka, Osaka, 560-8521, Japan.
authors.forename: Kenya
authors.initials: K
authors.lastname: Higashihara
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Toyonaka, Osaka, 560-8521, Japan.
authors.forename: Himanshu Sekhar
authors.initials: HS
authors.lastname: Jena
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Toyonaka, Osaka, 560-8521, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Higashida
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Toyonaka, Osaka, 560-8521, Japan. mashima@chem.es.osaka-u.ac.jp.
authors.forename: Kazushi
authors.initials: K
authors.lastname: Mashima
keywords: asymmetric catalysis; hydrogenation; reaction mechanisms; rhodium