Enantioselective synthesis of 2,2-disubstituted terminal epoxides via catalytic asymmetric Corey-Chaykovsky epoxidation of ketones.
Catalytic asymmetric Corey-Chaykovsky epoxidation of various ketones with dimethyloxosulfonium methylide using a heterobimetallic La-Li(3)-BINOL complex (LLB) is described. The reaction proceeded smoothly at room temperature in the presence of achiral phosphine oxide additives, and 2,2-disubstituted terminal epoxides were obtained in high enantioselectivity (97%-91% ee) and yield ( > 99%-88%) from a broad range of methyl ketones with 1-5 mol% catalyst loading. Enantioselectivity was strongly dependent on the steric hindrance, and other ketones, such as ethyl ketones and propyl ketones resulted in slightly lower enantioselectivity (88%-67% ee).
Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan. toshihiko-sone@ds-pharma.co.jp
Toshihiko
T
Sone
Akitake
A
Yamaguchi
Shigeki
S
Matsunaga
Masakatsu
M
Shibasaki
D002384:Catalysis; D004852:Epoxy Compounds / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D021241:Spectrometry, Mass, Electrospray Ionization; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism
D004852:Epoxy Compounds; D007659:Ketones