Catalytic Asymmetric γ‐Lactam Synthesis from Enolisable Anhydrides and Imines

An anion‐binding approach to the problem of preparing enantioenriched γ‐lactams from enolisable anhydrides and imines is reported. A simple bisurea catalyst promotes the cycloaddition between α‐aryl succinic anhydrides and either PMP‐ or benzhydryl‐protected aldimines to provide γ‐lactams with two contiguous stereocentres (one quaternary) with complete diastereocontrol and high to excellent enantioselectivity for the first time. A DFT study has provided insight into the catalyst mode of action and the origins of the observed stereocontrol. The scope of the asymmetric cycloaddition between simple imines and anhydrides has been expanded to include highly enantioselective synthesis of γ‐lactams for the first time.