Palladium-Catalyzed Regiospecific peri- and ortho-C–H Oxygenations of Polyaromatic Rings Mediated by Tunable Directing Groups

An efficient divergent approach of Pd-catalyzed C–H oxygenation of polyaromatic rings is described. Reversible directing groups enable regiospecific peri- and ortho-oxygenation to readily access a wide array of polyaromatic phenols without pre- and postmanipulation of directing groups. The systematic mechanistic investigation, including deuterium-labeling experiments, palladacycle trapping, and DFT calculations, reveals that the tunable ligand-assisted C–H bond cleavage played a crucial role during the reaction process.