Selected applications to organic synthesis of intramolecular C-H activation reactions by transition metals

Cyclometallated compounds obtained via the well-known intramolecular C-H activation by transition metals of N-or S-containing ligands may lead to organic heterocycles through reaction with alkynes.The mechanistic implications of the formation of both C-C and C-Y bonds are discussed.A reaction pathway involving insertion of the alkyne into the metalcarbon bond of the starting material followed by intramolecular addition of the Y atom to the resulting metallated-vinyl unit is proposed based on both the regioselectivity of the insertion and the existence of genuine isolated intermediates for the formation of the heterocyclic compounds.