C–H coupling reactions directed by sulfoxides: teaching an old functional group new tricks

Sulfoxides are classical functional groups for directing the stoichiometric metalation and functionalization of C−H bonds. In recent times, sulfoxides have been given a new lease on life owing to the development of modern synthetic methods that have arisen because of their unique reactivity. They have recently been used in catalytic C−H activation proceeding via coordination of an internal sulfoxide to a metal or through the action of an external sulfoxide ligand. Furthermore, sulfoxides are able to capture nucleophiles and electrophiles to give sulfonium salts, which subsequently enable the formation of C−C bonds at the expense of C−H bonds. This Review summarizes a renaissance period in the application of sulfoxides arising from their versatility in directing C−H functionalization.