Proton-Coupled Electron Transfer: An Overlooked Pathway for Initiating Chemical Reactivity with Thioxanthone as a Photocatalyst.

Thioxanthone, a well-known photocatalyst, is shown to participate in proton-coupled electron transfer based on the reactive substrate employed in photochemical transformation. This mode of reactivity can be manipulated to overcome the endergonicity of electron transfer pathways, leading to chemical reactivity via the formation of a thioxanthyl ketyl radical.