Here, we report a visible-light-mediated [2 + 2 + 1] cascade cyclization of 1,6-enynes with thiols, providing a new synthetic protocol for the rapid construction of sulfur-containing polycyclic derivatives in moderate to good yields along with a broad substrate scope. Mechanistic investigations were also performed through control experiments and Stern–Volmer analysis as well as DFT calculations, suggesting that this cascade cyclization reaction stems from a sulfur radical addition to the alkynyl moiety of 1,6-enyne along with a cascade cyclization with the alkenyl unit. Then, the formation of sulfur-containing polycyclic molecules can be achieved by homolytic S_Hi-type substitution at the thioether unit, stripping away a sulfur atom. Further transformations of the obtained product have also been disclosed.

中文翻译：

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光氧化还原催化级联 [2 + 2 + 1] 1,6-烯炔与硫醇环化

在这里，我们报道了可见光介导的 1,6-烯炔与硫醇的 [2 + 2 + 1] 级联环化，为快速构建中等至良好产率的含硫多环衍生物提供了一种新的合成方案广泛的底物范围。还通过控制实验、Stern-Volmer 分析以及 DFT 计算进行了机理研究，表明该级联环化反应源于硫自由基加成到 1,6-烯炔的炔基部分以及与烯基单元的级联环化。然后，通过硫醚单元上的均裂_SH i型取代，除去硫原子，可以形成含硫多环分子。还公开了所得产物的进一步转化。