Transition metal-catalysed C-H functionalization and decarboxylative coupling are two of the most notable synthetic strategies developed in the past 30 years. Here, we connect these two reaction pathways using bases and a simple Pd-based catalyst system to promote a para-selective C-H functionalization reaction from benzylic electrophiles. Experimental and computational mechanistic studies suggest a pathway that involves an uncommon Pd-catalysed dearomatization of the benzyl moiety followed by a base-enabled rearomatization through a formal 1,5-hydrogen migration. This reaction complements 'C-H activation' strategies that convert inert C-H bonds into C-metal bonds prior to C-C bond formation. Instead, this reaction exploits an inverted sequence and promotes C-C bond formation prior to deprotonation. These studies provide an opportunity to develop general para-selective C-H functionalization reactions from benzylic electrophiles and show how new reactive modalities may be accessed with careful control of the reaction conditions.

中文翻译：

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使用简单的胺连接远程CH键官能化和脱羧偶联。

过渡金属催化的CH官能化和脱羧偶联是过去30年来开发的最著名的两种合成策略。在这里，我们使用碱和简单的基于Pd的催化剂体系连接这两个反应路径，以促进由苄基亲电试剂进行的对位CH官能化反应。实验和计算机制研究表明，该途径涉及罕见的Pd催化的苄基部分脱芳香化作用，然后通过正式的1,5-氢迁移进行碱能的重新芳构化。该反应是“ CH活化”策略的补充，该策略可在CC键形成之前将惰性CH键转换为C-金属键。取而代之的是，该反应利用了反向序列并促进了去质子化之前CC键的形成。