Visible‐Light‐Driven Photocatalytic Methanol Activation on Hexagonal CdS for Triggering C─H Methylation

Abstract Light‐driven methanol activation paves the way for pursuing C─H methylation of N ‐heteroarenes, where selectively converting methanol into the corresponding hydroxymethyl radical (•CH 2 OH) is an essential prerequisite. Inspired by the versatile methanol activation on photoexcited solids, we here report a practicable semiconductor‐based photocatalytic system for C─H methylation of N ‐heteroarenes. To be specific, hexagonal cadmium sulfide ( h ‐CdS) was identified to be an ideal platform for visible‐light‐driven photocatalytic methanol activation, where selective •CH 2 OH generation undergoing a hole‐transfer process without any additional co‐catalysts or co‐solvent could trigger C─H hydroxymethylation of N ‐heteroarenes. The following electron transfer between photoexcited h ‐CdS and hydroxymethylated intermediates could finally lead to the formation of methylated N ‐heteroarenes. The transformations facilitate the cascade utilization of photoinduced hole and electron, thereby endowing h ‐CdS with extraordinary photocatalytic performance. Besides, selective generation of hydroxymethylated/methylated product could be facilely implemented in the presence/absence of electron scavengers.