Collaborative Interaction of Carbon–Carbon Unsaturated Bond Groups with Transition-metal Catalysts for C–H Bond Functionalization

Alkynes, alkenes, and thiophenes are found to behave as a directing group for C–H bond activation by a transition-metal catalyst. This collaborative interaction led to the discovery of not only simple intramolecular cyclizations but also carbon–carbon bond formation or annulation reactions with other reactants involving such unsaturated bond-directing groups. This highlight review discusses the recent progress in this sort of novel synthetic tools.