title: Efficient Access to Chiral Benzhydrols via Asymmetric Transfer Hydrogenation of Unsymmetrical Benzophenones with Bifunctional Oxo-Tethered Ruthenium Catalysts.
abstract: A concise asymmetric transfer hydrogenation of diaryl ketones, promoted by bifunctional Ru complexes with an etherial linkage between 1,2-diphenylethylenediamine (DPEN) and η(6)-arene ligands, was successfully developed. Because of the effective discrimination of substituents at the ortho position on the aryl group, unsymmetrical benzophenones were smoothly reduced in a 5:2 mixture of formic acid and triethylamine with an unprecedented level of excellent enantioselectivity. For the non-ortho-substituted benzophenones, the oxo-tethered catalyst electronically discerned biased substrates, resulting in attractive performance yielding chiral diarylmethanols with >99% ee.
authors.affiliation: Corporate Research & Development Division, Takasago International Corporation , 1-4-11 Nishi-Yawata, Hiratsuka, Kanagawa 254-0073, Japan.
authors.forename: Taichiro
authors.initials: T
authors.lastname: Touge
authors.affiliation: Corporate Research & Development Division, Takasago International Corporation , 1-4-11 Nishi-Yawata, Hiratsuka, Kanagawa 254-0073, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Nara
authors.affiliation: Corporate Research & Development Division, Takasago International Corporation , 1-4-11 Nishi-Yawata, Hiratsuka, Kanagawa 254-0073, Japan.
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Fujiwhara
authors.affiliation: Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology , 2-12-1-E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Kayaki
authors.affiliation: Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology , 2-12-1-E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Ikariya