Green Photoorganocatalytic Synthesis of Phenols from Arylboronic Acids

A green and cheap protocol for the photocatalytic hydroxylation of arylboronic acids is presented. 2,2-Dimethoxy-2-phenylacetophenone proved to be the best photoinitiator, among a range of organocatalysts in promoting this reaction. This photocatalytic protocol can be expanded into a wide substrate scope of aromatic boronic acids bearing various functional groups, leading to the corresponding phenols in good to high yields under mild reaction conditions, which include water as solvent, light irradiation provided from standard light-bulbs at room temperature.