Direct Allylic C(sp3)−H and Vinylic C(sp2)−H Thiolation with Hydrogen Evolution by Quantum Dots and Visible Light

Abstract

AbstractDirect allylic C−H thiolation is straightforward for allylic C(sp3)−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(sp3)−H thiolation has proved difficult. Represented herein is an exceptional for direct, efficient, atom‐ and step‐economic thiolation of allylic C(sp3)−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 (H2) is produced as byproduct. When vinylic C(sp2)−H was used instead of allylic C(sp3)−H bond, the radical‐radical cross‐coupling of C(sp2)−H and S−H was achieved with liberation of H2. Such a unique transformation opens up a door toward direct C−H and S−H coupling for valuable organosulfur chemistry.