Copper-Catalyzed β-Lactam Formation Initiated by 1,3-Azaprotio Transfer of Oximes and Methyl Propiolate.

A copper(II)-catalyzed protocol to construct trans-configured β-lactams and spirocyclic β-lactams from oximes and methyl propiolate has been developed, which features excellent substrate flexibility and diastereoselectivity (up to >99:1 dr). In situ FT-IR mechanistic experiments support that ketene species might be involved in the formation of β-lactams.