Iron phthalocyanine-catalyzed aerobic homo-coupling of phenols and cross-coupling of phenols with naphthols.

An iron(II) phthalocyanine (FePc)-catalyzed protocol has been developed for the aerobic oxidative coupling of phenols and naphthols in hexafluoroisopropanol at room temperature. Using air as the terminal oxidant, the method enables the homo-coupling of substituted phenols and naphthols as well as the cross-coupling of phenols with naphthols, while avoiding stoichiometric peroxide additives and affording biphenol products in up to 99% yield. Mechanistic studies and UV-vis analysis are consistent with a radical pathway involving a possible high-valent Fe(IV)-oxo species. FePc can be recycled for ten consecutive runs without significant loss of catalytic activity.