Palladium-Catalyzed Regioselectivity C─H Oxidation of Aromatics Utilizing Removable Directing Group Strategy

An efficient pyridine-assisted o-acetoxylation of 2-phenoxypyridines has been developed using AcOH as solvent and acetoxy source through Pd(II)-catalyzed C─H bond activation. The protocol exhibits high regioselectivity and functional group tolerance with yields up to 89%. Moreover, the 2-pyridyloxyl and acetyl groups can be readily removed, which provides indirect access to obtain pyrocatechol. Control experiments indicate that the reaction involves free radical pathway and C─H activation may be the rate-determining step.