title: Asymmetric conjugate reduction of alpha,beta-unsaturated ketones and esters with chiral rhodium(2,6-bisoxazolinylphenyl) catalysts.
abstract: New asymmetric conjugate reduction of beta,beta-disubstituted alpha,beta-unsaturated ketones and esters was accomplished with alkoxylhydrosilanes in the presence of chiral rhodium(2,6-bisoxazolinylphenyl) complexes in high yields and high enantioselectivity. (E)-4-Phenyl-3-penten-2-one and (E)-4-phenyl-4-isopropyl-3-penten-2-one were readily reduced at 60 degrees C in 95 % ee and 98 % ee, respectively, by 1 mol % of catalyst loading. (EtO)2MeSiH proved to be the best hydrogen donor of choice. tert-Butyl (E)-beta-methylcinnamate and beta-isopropylcinnamate could also be reduced to the corresponding dihydrocinnamate derivatives up to 98 % ee.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kanazawa
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Tsuchiya
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Takushi
authors.initials: T
authors.lastname: Shiomi
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Itoh
authors.forename: Makoto
authors.initials: M
authors.lastname: Kikuchi
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Hisao
authors.initials: H
authors.lastname: Nishiyama