1,2-and 1,4- addition to conjugated acceptors catalyzed by Lewis base

The 1,2- and 1,4-addition of N-Heterocyclic Carbenes (NHCs) to α,β-unsaturated carbonyl compounds results in the formation of α,β-unsaturated acyl azoliums, and β-azolium ylide intermediates, which engage in coupling with electrophiles, achieving to the synthesis of carbocyclic compounds.