Huang Cheng, Ci Rui-Nan, Qiao Jia, Wang Xu-Zhe, Feng Ke, Chen Bin, Tung Chen-Ho, Wu Li-Zhu
Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry & University of, Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Angew Chem Int Ed Engl. 2021 May 17;60(21):11779-11783. doi: 10.1002/anie.202101947. Epub 2021 Apr 14.
Direct allylic C-H thiolation is straightforward for allylic C(sp )-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 )-H thiolation has proved difficult. Represented herein is an exceptional for direct, efficient, atom- and step-economic thiolation of allylic C(sp )-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 ) is produced as byproduct. When vinylic C(sp )-H was used instead of allylic C(sp )-H bond, the radical-radical cross-coupling of C(sp )-H and S-H was achieved with liberation of H . Such a unique transformation opens up a door toward direct C-H and S-H coupling for valuable organosulfur chemistry.
直接烯丙基C-H硫醇化反应对于形成烯丙基C(sp³)-S键来说是直接可行的。然而，硫醇与过渡金属催化剂之间的强相互作用会导致催化循环失活或在氧化条件下硫原子被氧化。因此，直接烯丙基C(sp³)-H硫醇化反应已被证明具有挑战性。本文展示了一种在可见光照射下对烯丙基C(sp³)-H和硫醇S-H进行直接、高效、原子经济和步骤经济的硫醇化反应的特殊方法。自由基捕获实验和电子顺磁共振（EPR）光谱确定了在光催化剂量子点（QDs）表面产生的烯丙基自由基和硫自由基。C-S键的形成不需要外部氧化剂和自由基引发剂，并且副产物是氢气（H₂）。当使用乙烯基C(sp²)-H代替烯丙基C(sp³)-H键时，实现了C(sp²)-H和S-H的自由基-自由基交叉偶联，并释放出H₂。这种独特的转化为有价值的有机硫化学的直接C-H和S-H偶联打开了一扇门。
