Asymmetric Cyclopropanation by Reaction of a γ-Chloromethylated Chiral Vinylic Sulfoxide with Allylmagnesium Bromide

Abstract

An optically active vinylic sulfoxide bearing a leaving group at the γ-position was stereoselectively transformed into a chiral cyclopropane by means of a Michael addition with an allylmagnesium bromide. The Michael induced ring-closure reaction requires both allylmagnesium bromide as a uncleophile and chloride as a leaving group for high diastereoselectivity. The absolute stereochemistry of the cycloadduct was confirmed by X-ray analysis.