Recent Advances in Visible-Light-Catalyzed C—C Bonds and C—Heteroatom Bonds Formation Using Sulfonium Salts

Sulfonium salts are one of the most important class of organosulfur (IV) compounds which have a positive charge on the sulfur center with three C-S bonds.Because of their bench-stable, easy synthesis, broad structural diversity, and rich reactivity, sulfonium salts are playing a significant role in synthetic chemistry.In recent years, visible-light promoted photoredox catalysis is rapidly developing into a powerful tool for organic synthesis.In this paper, the recent advances of different sulfonium salts in the radical type reactions induced by visible light are summarized.The formation reactions of C-C bond and C-X (X＝B, N, O, S, Se, Te, F, Cl, I) bonds are introduced, and the applicable scope and mechanism of some reactions are also discussed.Keywords sulfur chemistry; sulfonium salt; visible light; free radical reaction 有机硫化合物在合成化学、生物医学和功能有机材 料领域扮演着极其重要的角色 [1] .据统计结果显示, 美 国销量排名前 200 位的药品中, 有 24.8%含有硫元素 [2] .硫原子与同族的氧原子相比, 其半径更大、电负性更低, 使得硫的外电子层更易于接受或提供电子, 显示出独特 的反应活性, 而硫鎓盐是中心硫原子与三个取代基相连 的带正电的有机硫化合物(通式为[R 3 S] ＋ X -).与同族氧 鎓盐相比, 硫鎓盐结构更加多样、热力学稳定性更强、 更易于合成、后处理更加简便 [3] .常见的硫鎓盐的合成方法如 Scheme 1 所示 [4] : (a)通 过二卤代烃与硫醇的亲核取代反应, 该方法制备硫鎓盐 操作简便, 结晶度好且稳定性高, 但主要局限于五元环 和六元环状硫鎓盐的制备.(b)采用硫醚和烷基卤化物通 过分子间亲核取代反应制备硫鎓盐, 该方法是目前应用 有机化学