Photocatalytic Hydroxyalkylation of Heteroarenes with Aldehydes

The photoredox hydroxyalkylation of heteroaromatics with aldehydes proceeds under mild and neutral conditions. This transition-metal- and oxidant-free hydroxyalkylation proceeds efficiently with various heteroarenes and aldehydes and has been applied to the late-stage modification of pharmaceutically active molecules, and on a gram-scale. (PhO)₂PO₂H plays multiple roles in this transformation, including protonation, hydrogen atom transfer (HAT) and electron transfer.