N-Heterocyclic carbene-catalyzed reactions of C-C unsaturated bonds.

The N-heterocyclic carbene-catalyzed reactions of C-X (X = O, S, N) unsaturated bonds are well established. However, C-C unsaturated bonds are challenging substrates for NHC-catalyzed reactions. In recent years, several reports have demonstrated that NHC-catalyzed reactions of C-C unsaturated bonds are feasible, including the umpolung of Michael acceptors, the Morita-Baylis-Hillman reaction, and the annulation reactions of vinyl sulfones, nitroalkenes, allenoates and alkynes.