Direct Allylic C(sp 3 )−H and Vinylic C(sp 2 )−H Thiolation with Hydrogen Evolution by Quantum Dots and Visible Light

Direct allylic C−H thiolation is straightforward for allylic C(sp 3 )−S bond formation. However, strong interactions between thiol and transition metal catalysts lead to deactivation of the catalytic cycle or oxidation of sulfur atom under oxidative condition. Thus, direct allylic C(sp 3 )−H thiolation has proved difficult. Represented herein is an exceptional for direct, efficient, atom‐ and step‐economic thiolation of allylic C(sp 3 )−H and thiol S−H under visible light irradiation. Radical trapping experiments and electron paramagnetic resonance (EPR) spectroscopy identified the allylic radical and thiyl radical generated on the surface of photocatalyst quantum dots (QDs). The C−S bond formation does not require external oxidants and radical initiators, and hydrogen (H 2 ) is produced as byproduct. When vinylic C(sp 2 )−H was used instead of allylic C(sp 3 )−H bond, the radical‐radical cross‐coupling of C(sp 2 )−H and S−H was achieved with liberation of H 2 . Such a unique transformation opens up a door toward direct C−H and S−H coupling for valuable organosulfur chemistry.