The deprotonation of propargylic C–H bonds for subsequent functionalization typically requires stoichiometric metal alkyl or amide reagents. In addition to the undesirable generation of stoichiometric metallic waste, these conditions limit the functional group compatibility and versatility of this functionalization strategy and often result in regioisomeric mixtures. In this Article, we report the use of dicarbonyl cyclopentadienyliron(II) complexes for the generation of propargylic anion equivalents toward the direct electrophilic functionalization of propargylic C–H bonds under mild, catalytic conditions. This technology was applied to the direct conversion of C–H bonds to C–C bonds for the synthesis of several functionalized scaffolds through a one-pot cross dehydrogenative coupling reaction with tetrahydroisoquinoline and related privileged heterocyclic scaffolds. A series of NMR studies and deuterium-labelling experiments indicated that the deprotonation of the propargylic C–H bond was the rate-determining step when a Cp*Fe(CO)2-based catalyst system was employed.

中文翻译：

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铁催化 π 键的 α-C–H 官能化：交叉脱氢偶联和机理见解


炔丙 C-H 键的去质子化以进行后续的官能化通常需要化学计量的金属烷基或酰胺试剂。除了产生不希望的化学计量金属废物外，这些条件还限制了该官能化策略的官能团相容性和多功能性，并且常常导致区域异构混合物。在本文中，我们报道了使用二羰基环戊二烯基铁 (II) 配合物生成炔丙阴离子等价物，从而在温和的催化条件下实现炔丙 C-H 键的直接亲电官能化。该技术应用于将C-H键直接转化为C-C键，通过与四氢异喹啉和相关特权杂环支架的一锅交叉脱氢偶联反应合成多种功能化支架。一系列 NMR 研究和氘标记实验表明，当采用 Cp*Fe(CO)2 基催化剂体系时，炔丙 C-H 键的去质子化是速率决定步骤。