Construction of N -Polyheterocycles by N -Heterocyclic Carbene Catalysis via a Regioselective Intramolecular Radical Addition/Cyclization Cascade.

N -Polyheterocycles are rapidly accessed by N -heterocyclic carbene (NHC) catalysis through regioselective sequential radical addition/cyclization in the absence of any metals or oxidants. The transformation occurs under mild conditions and enjoys a wide substrate scope with excellent functional group compatibility. Furthermore, a gram-scale synthesis is also conducted. Preliminary mechanistic studies reveal the potential involvement of an NHC radical cation intermediate.