Carbene-catalyzed enantioselective addition of benzylic carbon to unsaturated acyl azolium for rapid synthesis of pyrrolo[3,2- c]quinolines

Abstract

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.