Convenient procedure for the stereospecific synthesis of optically active alkyl S-alkyl methylphosphonothioates, dialkyl S-alkyl phosphorothioates, dialkyl methylphosphonates, and trialkyl phosphates

Abstract

Starting from the optically active cyclic esters prepared from ephedrine and RPSCl₂(R = Cl or Me), optically active alkyl S-methyl methylphosphonothioates and dialkyl S-methyl phosphorothioates are isolated in yields of 32–60%, by a sequence which permits the assignment of absolute configuration to the products; bromine promoted methanolysis of the S–Me derivatives affords the corresponding O-methyl esters with inversion of configuration at phosphorus.