Lukasevics Lukass, Oh George N, Wang Xiqu, Grigorjeva Liene, Daugulis Olafs
Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United States.
Latvian Institute of Organic Synthesis, Riga LV-1006, Latvia.
J Am Chem Soc. 2025 Jan 22;147(3):2476-2490. doi: 10.1021/jacs.4c13086. Epub 2025 Jan 10.
Monoanionic, bidentate-auxiliary-directed, cobalt-catalyzed C-H bond functionalization has become a very useful tool in organic synthesis. A comprehensive investigation into isolated organometallic intermediates and their reactivity within the catalytic cycle is lacking. We report here mechanistic studies of cobalt-catalyzed, aminoquinoline-directed C(sp)-H bond functionalization. A number of organometallic Co(III) intermediates have been isolated and structurally characterized, including, for the first time in the aminoquinoline system, complexes arising from migratory insertion into cobalt-carbon bonds. The catalytic and stoichiometric reactions of cobalt(III) aryls with alkenes, alkynes, carbon monoxide, cyclic secondary amines, and aminoquinoline benzamides have been explored. The oxidation state of cobalt intermediates in the product-forming step depends on the nature of the coupling component. Specifically, annulation with alkynes and carbonylation with CO likely proceed via a Co(I)/Co(III) catalytic cycle. Carbon-hydrogen bond functionalization with alkenes and amines, as well as benzamide homocoupling, likely proceed via a (formally) Co(IV) species and involve oxidatively induced reductive elimination.
单阴离子、双齿导向基团辅助的钴催化碳氢键官能化已成为有机合成中非常有用的工具。目前缺乏对分离出的有机金属中间体及其在催化循环中的反应活性的全面研究。我们在此报告钴催化、氨基喹啉导向的C(sp)-H键官能化的机理研究。已分离并对多种有机金属Co(III)中间体进行了结构表征，其中包括在氨基喹啉体系中首次出现的因迁移插入钴-碳键而产生的配合物。已探索了钴(III)芳基与烯烃、炔烃、一氧化碳、环状仲胺和氨基喹啉苯甲酰胺的催化反应和化学计量反应。产物形成步骤中钴中间体的氧化态取决于偶联组分的性质。具体而言，与炔烃的环化反应和与CO的羰基化反应可能通过Co(I)/Co(III)催化循环进行。与烯烃和胺的碳氢键官能化反应以及苯甲酰胺的均偶联反应可能通过（形式上的）Co(IV)物种进行，并涉及氧化诱导的还原消除。
