Pd-Catalyzed Hydroxylation of Aryl Boronic Acids Using In Situ Generated Hydrogen Peroxide.

Herein, we describe a benign and efficient palladium-catalyzed hydroxylation of aryl boronic acids under mild conditions, with in situ generated hydrogen peroxide from carbon monoxide, water, and oxygen. This novel procedure combines catalytic production of hydrogen peroxide with an aerobic oxidation process in a sole reaction system. This system shows good functional group tolerance and provides a benign and efficient access to a variety of functionalized phenols. Furthermore, the in situ generated hydroperoxide can be well used for triphenylphosphine oxidation, in which the TON is up to 194. Isotope labelling studies provide important mechanistic insights for this process.