Metal Catalyst-Free Oxidative Cleavage of Aryl C(OH)-C Bonds

A simple and efficient protocol for oxidative cleavage of aryl C(OH)-C bonds to acids was reported. In this protocol, KOtBu was found to be able to transform aryl alcohols and ketones to the desired benzoic acids without any other additives using 4 MPa O2 in mesitylene. Substrates with either electron-donating or electron-withdrawing groups could be transformed to the according benzoic acids in moderate to excellent yield. All these findings indicated that this oxidation of aryl secondary C(OH)-C bonds might proceed through a radical mechanism. And the represent lignin dimer model compound was successfully transformed to the benzoic acid, which indicated this protocol might has the potential to transform nature lignin. KOtBu was found to be able to transform aryl alcohols and ketones to the desired benzoic acids without any other additives using 4 MPa O2 in mesitylene. All aryl C(OH)-C bond in substrates with either electron-donating or electron-withdrawing groups could be transformed to the according benzoic acids in moderate to excellent yields. All findings indicated that the oxidation of aryl secondary C(OH)-C bonds might proceed through a radical mechanism.+image