Carbamoyl-substituted N-heterocyclic carbene complexes of palladium(II):: Application to Sonogashira cross-coupling reactions

[GRAPHIC] The first examples of N-carbamoyl-substituted heterocyclic carbene Pd(II) complexes are described, These thermal and hydrolytically stable complexes are readily prepared from carbamoyl imidazolium salts and efficiently promote Sonogashira cross-coupling reactions under mild conditions. Cesium carbonate is also shown to be an effective base for the coupling of aryl bromides.