title: Indolyl-oxazaphosphorine Precursors for Stereoselective Synthesis of Phosphite Triesters and Dithymidinyl Phosphorothioates.
abstract: Several novel chiral indolyl-oxazaphosphorines 7 were synthesized, and their potential as precursors to chiral phosphorothioates was evaluated. Reaction of 7 with a thymidine derivative gave phosphite triester 8 with a large degree of stereoselectivity. Sulfurization with Beaucage's reagent provided phosphorothioate triesters 9. The chiral auxiliary 9b containing a cyano group could be easily removed with aqueous ammonia to form dithymidinyl phosphorothioate in more than 97% diastereomeric excess. The chiral indolyl-oxazaphosphorines 7 are a new class of precursors for stereoselective synthesis of phosphorothioates.
authors.affiliation: Department of Chemistry, McGill University, Montreal H3A 2K6, Canada.
authors.forename: Jian-Chao
authors.initials: JC
authors.lastname: Wang
authors.forename: George
authors.initials: G
authors.lastname: Just