Catalytic Asymmetric γ-Lactam Synthesis from Enolisable Anhydrides and Imines

An anion-binding approach to the problem of preparing enantioenriched gamma-lactams from enolisable anhydrides and imines is reported. A simple bisurea catalyst promotes the cycloaddition between alpha-aryl succinic anhydrides and either PMP- or benzhydryl-protected aldimines to provide gamma-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.