An N-heterocyclic carbene-catalyzed enantioselective [3+2] annulation of enals with propargylic imines: access to gamma,gamma-disubstituted pyrrolidin-2-ones bearing quaternary stereogenic centers

An N-heterocyclic carbene-catalyzed asymmetric [3 + 2] annulation of enals with propargylic ketimines for the facile and enantioselective construction of gamma,gamma-disubstituted pyrrolidin-2-ones has been developed. This potocol was featured with mild reaction conditions, wild functional group tolerance, easy scalability, and high level of enantioselectivity, which also enriched the chemistry of NHC-bound homoenolates involved synthesis of gamma-lactams bearing gamma-quaternary stereogenic centers from acyclic kitimimes.