Reductive Hydroxymethylation of 4-Heteroarylpyridines

Article abstract of DOI:10.1002/chem.202000060

The activation of pyridinium salts with electron-withdrawing heterocycles enables an iridium-catalyzed reductive hydroxymethylation reaction to proceed smoothly, facilitating the preparation of useful 3D heteroaryl-substituted functionalized piperidines. The methodology is used to prepare 3-hydroxymethylated analogues of pharmaceutical agents. Mechanistically, formaldehyde acts as both a hydride donor and the electrophile, leading to the formation of two new carbon–hydrogen bonds and one new carbon–carbon bond under relatively mild conditions.