Asymmetric Synthesis of α,β-Epoxy-γ-lactams through Tandem Darzens/Hemiaminalization Reaction.

A catalytic asymmetric tandem Darzens/hemiaminalization reaction of glyoxals with α-bromo-β-esteramides or α-bromo-β-ketoamide was accomplished in the presence of a chiral N,N'-dioxide/Yb(III) complex. Various chiral α,β-epoxy-γ-lactams were obtained in moderate to good yields with excellent diastereo- and enantioselectivities. The versatility of the transformation is illustrated in the formal synthesis of berkeleyamide D.