C-C coupling with sulfur-stabilized carbanions, 9 - Reaction of the carbanions of 2-(alkylthio)thiolane 1-oxides with oxiranes

Carbanions of the 2-(alkylthio)thiolane 1-oxides 1 and 2 are generated and subjected to reaction with the epoxides 3-5. The resulting carbinols 6-11 a re formed with high a diastereoselectivity, which is explained by a stabili zation of the trans configuration of the carbanions in the activated comple x. A minor gamma stereoselectivity is also observed in case of the reaction s with 4 and 5. The pure enantiomers (1S,2S,2'S)-9a and (1R,2R,2'S)-11b wer e obtained from 2 and (S)-4 or (R)-5, respectively, and their configuration s were proved by X-ray structural analyses.