γ-Carbon Activation through N-Heterocyclic Carbene/Brønsted Acids Cooperative Catalysis: A Highly Enantioselective Route to δ-Lactams.

A γ-carbon activation method that operates through N-heterocyclic carbene/Brønsted acid cooperative catalysis for highly enantioselective synthesis of δ-lactams is reported. The protocol allows the challenging remote γ-carbon control of regioselectivity and enantioselectivity through introduction of an appropriate γ-leaving group in the enals. The reaction offers good yields and excellent enantioselectivities, and the resulting cyclic products can be easily converted into high-value drug-like derivatives.