Diastereoselective Alkylations of Sulfenate Anions

1. Adrian L. Schwan Department of Chemistry University of Guelph Guelph, ON, Canada Diastereoselective Alkylations of Sulfenate Anions Sulfenate anions represent a underexplored reactive entity in organic chemistry. They have been implicated in the action of the antibiotic leinamycin and their intermediacy in some biochemical oxidations and enzyme mechanisms has recently been recognized. In the laboratory sulfenates can be generated from b-sulfinyl acrylates and the chemistry is sufficiently mild to permit the release of cysteinesulfenate 1. Of particular interest is the stereoselective sulfur alkylation chemistry of 1 as a source of enriched cysteinyl sulfoxides (2). Using a selection of benzyl bromides, sulfenate 1 is alkylated with diastereoselectivities ranging from 89:11 to 95:5 (14 examples) . In the burgeoning field of sulfenate chemistry these values are quite significant. Through experimetns with 12-crown-4, it is proposed that internal complexation with lithium brings about the stereoselectivity. Working with chirality in the electrophile, it has also been established that simple sulfenates can alkylate with comparable diasteroselectivities as shown to the right.