Regiodivergent Ligand-Controlled Cobalt-Catalyzed Reductive Hydroxymethylation of Alkynes with Aqueous Formaldehyde.

Allylic alcohols are versatile and essential building blocks in synthetic chemistry, widely used for the preparation of complex molecules, pharmaceuticals, and materials. We report here a regiodivergent reductive hydroxymethylation of terminal alkynes with aqueous formaldehyde to prepare allylic alcohols enabled by visible light photoredox and cobalt dual catalysis. Using readily available, bulk, and cheap aqueous formaldehyde as a simple C1 source, this method allows for the selective production of both linear and branched allylic alcohols in one-step manner.