Stereoselective reaction of alpha-sulfinyl carbanion derived from chiral 2-(trialkylsilyl)ethyl sulfoxides: Evidence for a novel silicon-oxygen interaction

Reactions of 'alpha-sulfinyl carbanions, derived from p-tolyl sulfoxides be aring various alkyl groups, with various electrophiles were examined. The r eaction of cr-sulfinyl carbanions, derived from the beta-silylethyl sulfoxi des, with ketones or trimethyl phosphate, gave the syn products with high s tereoselectivity. Interaction between the silicon in the trialkylsilyl grou p and the carbonyl oxygen in nucleophiles was postulated to stabilize the t ransition state, leading preferably to the syn diastereisomers. This novel silicon-oxygen interaction was supported by an MO calculation study using t he MOPAC 93/PM3 and the Gaussian 94 Beche3LYP/3-21+G* methods.