Aldol reactions of unsubstituted beta-lactams. Studies of a beta-glycine enolate equivalent

Aldol reactions of the lithium enolate of N-(4-methoxybenzyloxy)azetidin-2-one (1) were examined. High diastereoselectivity favoring the anti adduct was observed with achiral aldehydes. Modest alpha-stereocontrol with chiral aldehydes was realized. Application of this method for the efficient synthesis of novel beta-amino esters is also described.