1,3,2-Thiazaphospholidin-2-ones derived from ephedrine. Preparation and stereochemistry of ring-opening reactions

Abstract

1,3,2-Thiazaphospholidin-2-ones are prepared by rearrangement of the corresponding 1,3,2-oxazaphospholidine-2-thiones. In both the phosphono- and phosphoro-series treatment with alkoxide results in P–N bond cleavage with inversion of configuration, while treatment with Grignard reagents results in P–S bond cleavage with retention of configuration. The products are consistent with a mechanism which involves initial nucleophilic attack opposite endocyclic nitrogen.