Acyl Azolium-Photoredox Enabled Synthesis of -Keto Sulfides

a-Heteroatom functionalization is a key strategy for C–C bond formation in organic synthesis, as exemplified by the addition of a nucleophile to electrophilic functional groups such as iminium ions, oxocarbenium ions and their sulfur analogs, sulfenium ions. We envisioned a photoredox-enabled radical Pummerer-type reaction realized through the single-electron oxidation of a sulfide. Following this oxidative event, ⍺-deprotonation affords ⍺-thioradicals that participate in radical-radical coupling reactions with azolium-bound ketyl radicals, accessing a commonly proposed mechanistic intermediate en route to functionalized additive Pummerer products. This system provides a new and complementary synthetic approach to highly functionalized sulfurous products and beckons further exploration in C-C bond formations previously limited in the standard two-electron process.