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 preand 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.

A total synthetic approach of hemigossypol is described with 10 steps in 9.5 % total yield with the key feature being successive ligand-directed proximal C-H oxygenations. Direct functionalization of the...