Deselenization of 1,2-diselenides offers a promising tool for the construction of organochalcogenides. However, the requirement of transition metals and harsh reaction conditions are still significant challenges in this transformation. Herein, we have developed a metal-free and catalyst-free photocatalytic system for deselenization of 1,2-diselenides with PCy₃, providing convenient access to monoselenides under mild conditions. Most importantly, the visible-light-induced protocol allowed for the deselenizative cross-coupling reaction between two different diselenides as well as the deselenizative cross-coupling reaction between a diselenide and a disulfide to provide unsymmetrical monoselenides and sulfides, respectively. DFT computational studies demonstrated that the chemoselectivity in the deselenizative cross-coupling reaction is derived from the difference in the C–Se bond dissociation energies as well as the polarity-matching effect. Mechanistic studies disclosed that the key to the deselenization lies in the generation of carbon-centered radicals through sequential Se–Se bond and C–Se bond cleavage of 1,2-diselenides.

中文翻译：

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可见光驱动的 PCy3 促进 1,2-二硒化物的脱硒化

1,2-二硒化物的脱硒为有机硫属化物的构建提供了一种有前途的工具。然而，过渡金属的需求和苛刻的反应条件仍然是这一转变的重大挑战。在此，我们开发了一种无金属、无催化剂的光催化系统，用于用PCy ₃脱硒1,2-二硒化物，从而在温和条件下方便地获得单硒化物。最重要的是，可见光诱导方案允许两种不同二硒化物之间的脱硒交叉偶联反应以及二硒化物和二硫化物之间的脱硒交叉偶联反应，分别提供不对称的单硒化物和硫化物。 DFT计算研究表明，脱硒交叉偶联反应的化学选择性源自C-Se键解离能的差异以及极性匹配效应。机理研究表明，脱硒化的关键在于通过1,2-二硒化物的连续Se-Se键和C-Se键断裂产生碳中心自由基。