Carbenes and Nitrenes

N-heterocyclic carbene catalyzed [2 + 3] annulation reaction for the synthesis of trifluoroethyl 3,2′-spirooxindole γ-lactam

“…N-heterocyclic carbenes (NHCs) 1 have been extensively adopted as an asymmetric synthetic catalyst for the synthesis of chiral heterocycles. The use of NHCs results in various powerful intermediates such as Breslow, 2 enolate, 3 homoenolate, 4 and unsaturated acylazolium, 5 which could undergo further [3 + 2], 6 [4 + 2] 7 annulation and more reactions.…”