A mechanistic study reveals the roles of the ligand and substrate in the Pd-catalyzed C–H bond hydroxylation of a carboxylic acid with molecular oxygen

DFT studies reveal critical factors influencing the reactivity of Pd-catalyzed C–H bond hydroxylation with O 2 : (1) substrate axial coordination; (2) proton shuttling by the ligand; and (3) dimeric palladium species formation.