LAUSR

A regioselective C–H arylation of substituted phenols or naphthols with substituted aromatics in the presence of K2S2O8 and Bu4N+·HSO4– in CF3COOH at ambient temperature providing unsymmetrical biaryls is described. The cross-coupling reaction is compatible with various substituted phenols and aromatics. Based on oxidation potential studies, it was observed that phenols with oxidation potentials up to 0.68 V and naphthols up to 0.88 V were compatible with the reaction. The cross-coupling reaction proceeds through the reaction of K2S2O8 with substituted phenol, providing a cationic phenol radical intermediate that was further converted into the phenoxy radical intermediate by the dissociation of H+. Subsequent radical-anion coupling of the phenoxy radical intermediate with a substituted aromatic affords the cross-coupling product. The formation of a cationic phenol radical intermediate and phenoxy radical intermediate were confirmed by UV/Vis and EPR studies.