SYNTHESIS OF SOME NEW SUGAR BASED 3, 3-DISUBSTITUTED MONOCYCLIC Β-LACTAMS BY ASYMMETRIC [2+2] CYCLOADDITION REACTIONS

Synthesis of some new monocyclic B-lactams containing a quaternary carbon center via a [2+2] cycloaddition reaction is described. The reaction of achiral diphenyl ketene with chiral aldimines derived from chiral 2, 3, 4, 6-tetra-O-acetyl-B-D-galactopyranosylamine, 2, 3, 4, 6-tetra-O-acetyl-B-D- glucopyranosylamine and different benzaldehydes resulted in the formation of B-lactams as single diastereomers.