Highly enantioselective addition of enals to isatin-derived ketimines catalyzed by N-heterocyclic carbenes: synthesis of spirocyclic γ-lactams.

An N-heterocyclic carbene (NHC)-catalyzed annulation reaction of isatin N-Boc ketimines and enals is developed for the synthesis of spirocyclic oxindole-γ-lactams bearing one quaternary chiral center in good yields and excellent stereoselectivities (up to >20:1 dr and 99% ee).