N-heterocyclic carbene:: a versatile organocatalyst

In recent years N-heterocyclic carbenes (NHC) have evoked considerable interest, and this can be attributed in large measure to the isolation of a stable imidazol-2-ylidene by Arduengo et al. in 1991. Although the use of NHC as ligands in organometallic reactions has been studied extensively, the study of N-heterocyclic carbenes used as the reaction reagents and catalysts still need to be conducted deeply. The purpose of this passage is to cast some light on the chemistry of NHC as organocatalysts and to inspire organic chemists to pay more attention to this hot field.