EFFICIENT PATHWAYS TO PRECURSORS OF PYRROLIDINE AZASUGAR STRUCTURES

Hydroxy-substituted pyrrolidines are important structural elements in azasugars. Effective precursors for such compounds are pyrrolo-oxazoli dinones of type 1. Short asymmetric syntheses starting from easily ava ilable low-priced precursors are desirable. Two efficient pathways to these structures starting from the 4-methoxylated oxazolidinones 2 and 3, easily accessible from the chiral pool, have been successfully dev eloped. These oxazolidinones can be used as amidoalkylation reagents. Via Sakurai reactions and subsequent intramolecular cyclization, the s ynthesis of bicyclic pyrrolidines is possible in a stereocontrolled wa y.