Merging carboxylic acids with metal-catalyzed hydrogen atom transfer (MHAT) chemistry via alkene-functionalized redox-active esters

Abstract

The development of general methods for radical bond formation remains a central goal in organic synthesis, particularly those that enable diverse transformations from simple, abundant starting materials. Here, we report a unified approach that merges carboxylic acid activation with metal-catalyzed hydrogen atom transfer (MHAT) to enable the generation and selective functionalization of open-shell intermediates under a single catalytic system. Key to this strategy is the design of a redox-active ester bearing an internal alkene “trigger” that undergoes regioselective MHAT using Fe(acac)₃ and phenylsilane, leading to decarboxylative radical formation under mild conditions. This platform supports the synthesis of a wide array of products via C–C, C–heteroatom, and C–H bond-forming processes, accessed solely by varying the radical acceptor. Notably, it enables the formation of linear coupling products—previously inaccessible under conventional MHAT conditions—via access to primary radical intermediates. We anticipate that this conceptually distinct mode of activation will find applications in modular synthesis, late-stage functionalization, and the generation of medicinally relevant analogs.