Weng Yuecheng, Jin Yuxuan, Wu Jian, Leng Xuebing, Lou Xiaobing, Geng Fushan, Hu Bingwen, Wu Botao, Shen Qilong
State Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China.
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China.
J Am Chem Soc. 2024 Aug 21;146(33):23555-23565. doi: 10.1021/jacs.4c07552. Epub 2024 Aug 8.
Copper-catalyzed coupling reactions of alkyl halides are believed to prominently involve copper(II) species and alkyl radicals as pivotal intermediates, with their exact interaction mechanism being the subject of considerable debate. In this study, a visible light-responsive fluoroalkylcopper(III) complex, [(terpy)Cu(CF)(CHCOBu)] , was designed to explore the mechanism. Upon exposure to blue LED irradiation, undergoes copper-carbon bond homolysis, generating Cu(II) species and carbon-centered radicals, where the carbon-centered radical then recombines with the Cu(II) intermediate, resulting in the formation of , the Cis isomer of . Beyond this, a well-defined fluoroalkylcopper(II) intermediate ligated with a sterically hindered ligand was isolated and underwent full characterization and electronic structure studies. The collective experimental, computational, and spectroscopic findings in this work strongly suggest that organocopper(II) engages with carbon-centered radicals via an "oxidative substitution" mechanism, which is likely the operational pathway for copper-catalyzed C-H bond trifluoromethylation reactions.
人们认为，卤代烃的铜催化偶联反应主要涉及铜（II）物种和烷基自由基作为关键中间体，其确切的相互作用机制一直是大量争论的主题。在本研究中，设计了一种可见光响应的氟烷基铜（III）配合物[（三联吡啶）Cu（CF）（CHCOBu）]来探索该机制。在蓝光发光二极管照射下，发生碳-铜键均裂，生成铜（II）物种和碳中心自由基，其中碳中心自由基随后与铜（II）中间体重新结合，导致生成的顺式异构体。除此之外，分离出一种与空间位阻配体相连的明确的氟烷基铜（II）中间体，并对其进行了全面表征和电子结构研究。这项工作中综合的实验、计算和光谱研究结果有力地表明，有机铜（II）通过“氧化取代”机制与碳中心自由基相互作用，这可能是铜催化C-H键三氟甲基化反应的操作途径。
