The copper-NHC-catalyzed carboxylation of organoboranes with CO₂ was investigated using computational and experimental methods. The DFT and DLPNO-CCSD(T) results indicate that nonbenzylic substrates are converted via an inner-sphere carboxylation of an organocopper intermediate, whereas benzylic substrates may simultaneously proceed along both inner- and outer-sphere CO₂ insertion pathways. Interestingly, the computations predict that two conceptually different carboxylation mechanisms are possible for benzylic organoboranes, one being copper-catalyzed and one being mediated by the reaction additive CsF. Our experimental evaluation of the computed reactions confirms that carboxylation of nonbenzylic substrates requires copper catalysis, whereas benzylic substrates can be carboxylated with and without copper.

中文翻译：

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机械观察铜催化的羧化反应

使用计算和实验方法研究了铜-NHC催化的有机硼烷与CO _2的羧化反应。DFT和DLPNO-CCSD（T）结果表明，非苄基底物通过有机铜中间体的内球羧基化而转化，而苄基底物可同时沿内球和外球CO _2进行插入途径。有趣的是，这些计算预测苄基有机硼烷有两种概念上不同的羧化机理，一种是铜催化的，另一种是由反应添加剂CsF介导的。我们对计算反应的实验评估证实，非苄基底物的羧化需要铜催化，而苄基底物可以在有铜和无铜的情况下进行羧化。