Liu Jian-Biao, Liu Xiao-Jun, Oliveira João C A, Chen De-Zhan, Ackermann Lutz
College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University Jinan 250014 China
Institut für Organische und Biomolekulare Chemie, Wöhler Research Institute for Sustainable Chemistry (WISCh), Georg-August-Universität Göttingen Tammannstraße 2 37077 Göttingen Germany
Chem Sci. 2023 Feb 28;14(12):3352-3362. doi: 10.1039/d2sc05200h. eCollection 2023 Mar 22.
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)-H activation in the coupling reaction occurs 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.
烯烃向金属 - 碳（M - C）键的迁移插入是多种催化过程中的基本步骤。在本工作中，通过计算揭示了一种涉及协同但不同步的M - C均裂和自由基进攻的自由基型迁移插入。受所提出的迁移插入的自由基性质启发，针对亚烷基环丙烷（ACP）提出了一种独特的钴催化自由基介导的碳 - 碳（C - C）裂解机制。这种独特的C - C活化是合理解释实验观察到的苯甲酰胺与ACP之间偶联选择性的关键。此外，偶联反应中的C(sp) - H活化通过质子耦合电子转移（PCET）机制发生，而不是最初提出的协同金属化 - 去质子化（CMD）途径。开环策略可能会刺激新型自由基转化的进一步发展和发现。
