Enantiopure α-hydroxy-β-lactams via stereoselective glycosylation

Abstract

Stereospecific glycosylation via the Ferrier rearrangement catalyzed by iodine has been used to obtain both enantiomers of a trans 4-aryl-3-hydroxy-2-azetidinone. Unexpectedly, a rhamnal derivative had to be employed for this reaction since a glucal derivative failed to work. This synthesis complements our previously described preparation of the corresponding cis isomers by the same methodology. Thus, convenient access has become available to all four homochiral stereoisomers of α-hydroxy-β-lactams some of which are synthons for Taxol ® and analogs.