Transition-metal mediated C–H functionalization has emerged as a powerful method in the chemistry relevant to the synthesis of pharmaceuticals, agrochemicals, and advanced materials. Because organic molecules typically contain multiple types of C–H bonds, selective C–H functionalization is a major ongoing challenge. C–H activation of heteroatom-containing organics has often been approached via the use of the directing effect, whereby the coordination to the basic heteroatom directs the reactive metal center to a specific C–H bond. We now report a different approach where the nitrogen donor in pyridine derivatives coordinates to an ancillary Lewis acidic boryl ligand directly attached to the metal (iridium) center, as opposed to the metal itself. This topology directs the iridium center to activate a different C–H bond than in the cases of directing donor coordination to the metal. Using this strategy, we demonstrate ortho-regiospecific C–H activation of pyridines and an example of the subsequent functionalization via C–C bond formation.

中文翻译：

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PBP钳铱铱配合物的路易斯酸性硼对吡啶的选择性邻位C–H活化作用

过渡金属介导的C–H功能化已成为化学领域中与药物，农药和先进材料合成相关的强大方法。由于有机分子通常包含多种类型的C–H键，因此选择性的C–H功能化是一个重大的持续挑战。含杂原子的有机物的C–H活化通常是通过使用导向作用来实现的，由此与基本杂原子的配位将反应性金属中心引导至特定的C–H键。现在我们报道一种不同的方法，其中吡啶衍生物中的氮供体与直接与金属（铱）中心相连的路易斯辅助酸性硼基配体配位，而不是与金属本身相反。与将供体配位到金属上的情况相比，这种拓扑结构指导铱中心激活不同的CH键。使用这种策略，我们证明了吡啶的邻位区域特异性C–H活化以及随后通过C–C键形成功能化的例子。