Cobalt-Catalyzed Monoselective Ortho-C–H Functionalization of Carboxamides with Organoaluminum Reagent

A simple triphenylphosphine-ligated cobalt catalyst is reported for the direct ortho-C–H methylation and ethylation of aromatic, heteroaromatic, alkenyl, and even aliphatic carboxamides with inexpensive organoaluminum reagents in the presence of a cheap alkyl chloride as oxidant. This reaction shows monoselectivity in contrast with previously established C–H methylation methodologies.