N-heterocyclic Carbene-Catalyzed Cascade Syntheses Of ?-Lactams,Spirocyclic Oxindole 4H-Pyran-2-Ones And Naphthodihydropyranones

N-heterocyclic carbenes(NHCs)can be used as nucleophilic reagents,Lewis base and Bronsted base in organocatalytic reactions.They have become one of the research hotspots in the fields of organocatalysis at present.Their structure can be modified by introducing different chiral groups to catalyze asymmetric reactions to provide enantioselective assemblies of cyclic skeletons.This paper mainly introduced the asymmetric construction of the ?-lacatam,spirocyclic oxindole-4H-pyran-2-one and naphthodihydropyranone.The main works are composed of four parts:Part one includes the introduction of the discovery,structural assignment,nature,common types,recent development of NHCs and the innovation of this research.The second part illustrates the acylhydrazones reacting with the ?-bromo-?,?-unsaturated aldehydes to construct the ?-lactams in the presence of NHCs.This approach features good yields,high enantioselectivity,ready availability of the raw materials and facile assembly.In part three,the construction of spirocyclic oxindole 4H-pyran-2-one ramifications via the bromoenals with oxindoles in the presence of NHCs is expounded.This approach features the ready availability of the starting materials,excellent diastereoselectivity,high yields.The fourth part describes a straightforward NHC-mediated syntheses of naphthodihydropyranones from bromoenals and ?-tetralones.The key advantages of this protocol include ready availability of starting materials,good yields,and excellent enantioselectivity.