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. This manuscript illustrated the o‐acetoxylation of 2‐phenoxypyridines using AcOH as acetoxy source through Pd(II)‐catalyzed C─H bond activation. This protocol exhibits high regioselectivity and functional group tolerance. Control experiments indicate that the reaction involves free radical pathway and C─H activation may be the rate‐determining step. Both 2‐pyridyloxy and acetyl groups on the product could be conveniently removed to obtain pyrocatechol. Thus, this protocol might provide a feasible approach for the synthesis of substituted pyrocatechols which are an important chemical intermediate.