Cobalt-catalyzed radical-mediated carbon-carbon scission via a radical-type migratory insertion

Migratory insertions of alkenes into metal-carbon (M-C) bonds are elementary steps in diverse catalytic processes. In the present work, a radical-type migratory insertion that involves concerted but asynchronous M-C homolysis and radical attack was revealed by computations. Inspired by the radical nature of the proposed migratory insertion, a distinct cobalt-catalyzed radical-mediated carbon-carbon (C-C) cleavage mechanism was proposed for alkylidenecyclopropanes (ACPs). This unique C-C activation is key to rationalizing the experimentally observed selectivity for the coupling between benzamides and ACPs. Furthermore, the C(sp(2))-H activation in the coupling reaction occurs via the proton-coupled electron transfer (PCET) mechanism rather than the originally proposed concerted metalation-deprotonation (CMD) pathway. The ring opening strategy may stimulate further development and discovery of novel radical transformations.

Automated summary

In this study, a radical-type migratory insertion involving synchronous but asynchronous metal-carbon (M-C) bond homolysis and radical attack was discovered through computations. Inspired by this radical migratory insertion, a distinct cobalt-catalyzed radical-mediated carbon-carbon (C-C) cleavage mechanism was proposed for alkylidenecyclopropanes (ACPs). This unique C-C activation mechanism plays a key role in explaining the experimentally observed selectivity for the coupling between benzamides and ACPs. Additionally, the C(sp(2))-H activation in the coupling reaction occurs via the proton-coupled electron transfer (PCET) mechanism instead of the originally proposed concerted metalation-deprotonation (CMD) pathway. The ring opening strategy may lead to further development and discovery of novel radical transformations.