Enantioselective synthesis of α,α-difluoro-β-lactams using amino alcohol ligands.

A practical and highly enantioselective Reformatsky reaction of ethyl bromodifluoroacetate with imines using a cheap and commercially available amino alcohol ligand is described. A variety of α,α-difluoro-β-lactams were obtained in up to 74% yield with high enantioselectivity in excess of 99% ee. The use of ethyl bromodifluoroacetate provides for ease of operation because of the inherent chemical stability of this reagent.