Photochemical Aldehyde–Olefin Coupling via In Situ Activation of α-Benzoyloxy Chlorides

Abstract While ketyl radicals enable powerful umpolung C(sp3)–C(sp3) couplings, their generation from aliphatic aldehydes typically requires metal reductants or precious-metal catalysts. Herein, we report a practical photochemical protocol for one-pot aldehyde–olefin cross-coupling. This method leverages the in situ formation of α-benzoyloxy chlorides, which undergo direct reduction by a photoexcited Hantzsch ester to afford ketyl-type radicals. This mild strategy features operational simplicity, broad functional group tolerance, and enables late-stage modification of bioactive molecules.