Rhodium-catalyzed regiospecific C-H ortho-phenylation of benzoic acids with Cu/air as an oxidant

The development of an efficient and practical synthetic approach for the regiospecific C-H ortho-phenylation of aromatic carboxylic acids without the use of silver or costly coupling partners is reported. The rhodium-catalyzed C-H phenylation proceeded in the presence of Cu/air as a terminal oxidant. In most cases, numerous inactivated benzoic acids could couple with low-cost NaBPh4 to obtain good to excellent yields.