Photo‐induced C 1  Substitution Using Methanol as a C 1  Source

The development of sustainable and efficient C1 substitution methods is of central interest for organic synthesis and pharmaceuticals production, the methylation motifs bounding to a carbon, nitrogen, or oxygen atom widely exist in natural products and top-selling drugs. In the past decades, a number of methods involving green and inexpensive methanol have already been disclosed to replace industrial hazardous and waste-generating C1 source. Among the various efforts, photochemical strategy is considered as a “renewable” alternative which shows great potential to selectively activate methanol to achieve a series of C1 substitutions at mild conditions, typically C/N-methylation, methoxylation, hydroxymethylation, and formylation. Here, we systematically reviewed the recent advances in selective transformation of methanol to various C1 functional groups via well-designed photochemical systems involving kinds of catalysts or not. Both the mechanism and corresponding photocatalytic system were discussed and classified on specific methanol activation models. Finally, the major challenges and perspectives are proposed.