Control of diastereoselectivity in the nucleophilic epoxidation of 1-arylthro-1-nitroalkenes: synthesis of diastereoisomerically pure γ-hydroxy threonine derivatives

Abstract

Epoxidation of the 1-nitro-1-(p-tolylthio)alkene 1 derived from D-isopropylideneglyceraldehyde with lithium tert-butyl peroxide affords the syn epoxide 2 with moderate selectivity, whereas epoxidation with potassium tert-butyl peroxide affords the anti diastereoisomer 3 preferentially; treatment of each of the epoxides 2 and 3 with amines, including ammonia, gives diastereoisomerically pure α-amino thioesters with no trace of stereoisomeric contamination.