Carbene-Catalyzed Enantioselective Addition of Benzylic Carbon to Unsaturated Acyl Azolium for Rapid Synthesis of Pyrrolo[3,2‑c]quinolines

A carbene-catalyzed enantioselective addition of benzylic carbon to α,β-unsaturated acyl azolium intermediate generated via N-heterocyclic carbene catalysis is disclosed. This addition is followed by a stereoselective Mannich reaction and a chemo-selective lactam formation cascade to afford pyrrolo­[3,2-c]­quinolones as the products with excellent yields and optical purities. This work constitutes an effective asymmetric benzyl sp3-carbon functionalization and single-step rapid access to multicyclic heterocycles bearing four contiguous chiral centers.