Process in N-Heterocyclic Carbene-Catalyzed Annulation Reactions

OBJECTIVE To introduce the process in N-heterocyclic carbene-catalyzed annulation reactions. METHODS To review both domestic and international published reports regarding N-heterocyclic carbene-catalyzed annulation reactions. RESULTS To make a list of N-heterocyclic carbene-catalyzed annulation reactions of intramolecular Stetter reaction, nucleophilic substitution reaction, cycloaddition and tandem reaction and to analyze N-heterocyclic carbene-catalyzed 4+2, 3+2, 2+2 and 3+3 cycloaddition specially. CONCLUSION The development of the N-heterocyclic carbene-catalyzed annulation reactions provides us new ways and strategies for efficient annulation.