Direct carbonylation at a C-H bond catalyzed by transition metal complexes

Transition-metal-catalyzed carbonylation with cleavage of a C-H bond is described. The reactions described are (i) carbonylation at the C-H bond alpha to the ring nitrogen in imidazoles (ii) carbonylation at the C-H bond gamma to the ring nitrogen in pyridylbenzenes, aromatic imines, and aryloxazolines (iii) carbonylation at the olefinic C-H bond in pyridylolefines (iv) carbonylation at the sp(2) C-H bond in a piperazine ring. Coordination of a directing group such as nitrogen or oxygen functionalities to transition metals, such as ruthenium and rhodium, promotes site selective cleavage of a C-H bond.