title: Searching for Practically Useful P-Chirogenic Phosphine Ligands.
abstract: In this account, the design, synthesis, and application of P-chirogenic phosphine ligands that have been mainly carried out in our laboratory over the last three decades are described. Various enantiopure P-chirogenic phosphine ligands have been efficiently prepared by using phosphine boranes as intermediates. Conformationally rigid and electron-rich P-chirogenic phosphine ligands possessing C2symmetry as well as a bulky alkyl group and a small group at the phosphorus atoms exhibit excellent enantioselectivities and catalytic efficiency in a variety of transition-metal-catalyzed asymmetric reactions. Enantiopure 2,3-bis(tert-butylmethylphosphino)quinoxaline (QuinoxP*) is an air-stable crystalline solid that shows superior enantioinduction ability in catalytic asymmetric syntheses. Mechanistic studies of Rh-catalyzed asymmetric hydrogenation using structurally simple P-chirogenic phosphine ligands, such as tBu-BisP*, are briefly described.
authors.affiliation: Organic R&D Department, Nippon Chemical Industrial Co., Ltd, Koto-ku, Tokyo, 136-8515, Japan.|Department of Chemistry, Graduate School of Science, Chiba University, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Imamoto
keywords: asymmetric synthesis; enantioselectivity; hydrogenation; ligand design; rhodium