To improve the efficacy of molecular syntheses, researchers wish to capitalize upon the selective modification of otherwise inert C-H bonds. The past two decades have witnessed considerable advances in coordination chemistry that have set the stage for transformative tools for C-H functionalizations. Particularly, oxidative C-H/C-H and C-H/Het-H transformations have gained major attention because they avoid all elements of substrate prefunctionalization. Despite considerable advances, oxidative C-H activations have been dominated by precious transition metal catalysts based on palladium, ruthenium, iridium, and rhodium, thus compromising the sustainable nature of the overall C-H activation approach. The same holds true for the predominant use of stoichiometric chemical oxidants for the regeneration of the active catalyst, prominently featuring hypervalent iodine(III), copper(II), and silver(I) oxidants. Thereby, stoichiometric quantities of undesired byproducts are generated, which are preventive for applications of C-H activation on scale. In contrast, the elegant merger of homogeneous metal-catalyzed C-H activation with molecular electrosynthesis bears the unique power to achieve outstanding levels of oxidant and resource economy. Thus, in contrast to classical electrosyntheses by substrate control, metalla-electrocatalysis holds huge and largely untapped potential for oxidative C-H activations with unmet site selectivities by means of catalyst control. While indirect electrolysis using precious palladium complexes has been realized, less toxic and less expensive base metal catalysts feature distinct beneficial assets toward sustainable resource economy. In this Account, I summarize the emergence of electrocatalyzed C-H activation by earth-abundant 3d base metals and beyond, with a topical focus on contributions from our laboratories through November 2019. Thus, cobalt electrocatalysis was identified as a particularly powerful platform for a wealth of C-H transformations, including C-H oxygenations and C-H nitrogenations as well as C-H activations with alkynes, alkenes, allenes, isocyanides, and carbon monoxide, among others. As complementary tools, catalysts based on nickel, copper, and very recently iron have been devised for metalla-electrocatalyzed C-H activations. Key to success were detailed mechanistic insights, prominently featuring oxidation-induced reductive elimination scenarios. Likewise, the development of methods that make use of weak O-coordination benefited from crucial insights into the catalyst's modes of action by experiment, in operando spectroscopy, and computation. Overall, metalla-electrocatalyzed C-H activations have thereby set the stage for molecular syntheses with unique levels of resource economy. These electrooxidative C-H transformations overall avoid the use of chemical oxidants and are frequently characterized by improved chemoselectivities. Hence, the ability to dial in the redox potential at the minimum level required for the desired transformation renders electrocatalysis an ideal platform for the functionalization of structurally complex molecules with sensitive functional groups. This strategy was, inter alia, successfully applied to scale-up by continuous flow and the step-economical assembly of polycyclic aromatic hydrocarbons.

中文翻译：

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富含地球的3d金属及其以外的金属电催化的CH活化。

为了提高分子合成的效率，研究人员希望利用对其他惰性CH键的选择性修饰。在过去的二十年中，配位化学取得了长足的进步，为CH功能化的转化工具奠定了基础。尤其是，氧化的CH / CH和CH / Het-H转换由于避免了底物预官能化的所有元素而备受关注。尽管取得了相当大的进步，但是氧化的CH活化已被基于钯，钌，铱和铑的贵重过渡金属催化剂所控制，从而损害了整个CH活化方法的可持续性。对于化学计量的化学氧化剂主要用于活性催化剂的再生，也是如此，突出显示高价碘（III），铜（II）和银（I）氧化剂。由此，产生化学计量的不期望的副产物，其对于大规模应用CH活化是预防性的。相比之下，均质金属催化的CH活化与分子电合成的完美结合具有独特的功能，可实现出色的氧化剂水平和资源经济性。因此，与传统的通过底物控制进行电合成相反，金属电催化通过催化剂控制具有巨大且尚未开发的氧化CH活化潜力，且具有未满足的位点选择性。尽管已经实现了使用贵重钯配合物的间接电解，但毒性较低，价格较便宜的贱金属催化剂具有有利于可持续资源经济的独特优势。在本报告中，我总结了地球上丰富的3d基本金属及其他材料对电催化CH活化的出现，并重点关注了我们的实验室在2019年11月之前的贡献。因此，钴电催化被认为是提供大量有机物的特别强大的平台。 CH转化，包括CH氧化和CH硝化，以及炔烃，烯烃，丙二烯，异氰化物和一氧化碳等的CH活化。作为补充工具，已经设计了基于镍，铜和最近铁的催化剂用于金属电催化的CH活化。成功的关键是详尽的机械洞察力，其主要特征是氧化诱导的还原消除方案。同样地，利用弱O配位的方法的开发得益于通过实验，操作光谱和计算对催化剂的作用方式的关键见解。总体而言，金属电催化的CH活化从而为具有独特资源节约水平的分子合成奠定了基础。这些电氧化的CH转化总体上避免了化学氧化剂的使用，并且通常以提高的化学选择性为特征。因此，以所需转化所需的最低水平拨入氧化还原电势的能力使电催化成为具有敏感官能团的结构复杂分子功能化的理想平台。除其他外，该战略是