Photocatalytic Methylation of Nonactivated sp3 and sp2 C–H Bonds Using Methanol on GaN

Although the development of C–H functionalization methods has enlightened many reactivities in chemistry, the direct functionalization of unactivated C–H bonds, which are particularly common in petroleum compounds, is still faced with great difficulty. Herein, we describe a photocatalytic approach that allows direct methylation of unactivated sp3 and sp2 C–H bonds using methanol as the methylation reagent, with gallium nitride as a powerful yet robust catalyst. Mechanistic studies suggested that the methanol is dehydrated into methyl carbene intermediate via a bimolecular mechanism.