Kinetic and thermodynamic control of C(sp2)-H activation enables site-selective borylation

• 成果类型: Article
• 署名作者: Roque, Jose B.; Shimozono, Alex M.; Pabst, Tyler P.; Hierlmeier, Gabriele; Peterson, Paul O.; Chirik, Paul J.
• 署名单位: Princeton University
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-12488
• DOI: 10.1126/science.adj6527
• 发表日期: 2023-12-08
• 页码: 1165-1170
• 关键词: c-h borylation; iridium catalysts; arenes; complexes; metal

摘要

Catalysts that distinguish between electronically distinct carbon-hydrogen (C-H) bonds without relying on steric effects or directing groups are challenging to design. In this work, cobalt precatalysts supported by N-alkyl-imidazole-substituted pyridine dicarbene (ACNC) pincer ligands are described that enable undirected, remote borylation of fluoroaromatics and expansion of scope to include electron-rich arenes, pyridines, and tri- and difluoromethoxylated arenes, thereby addressing one of the major limitations of first-row transition metal C-H functionalization catalysts. Mechanistic studies established a kinetic preference for C-H bond activation at the meta-position despite cobalt-aryl complexes resulting from ortho C-H activation being thermodynamically preferred. Switchable site selectivity in C-H borylation as a function of the boron reagent was thereby preliminarily demonstrated using a single precatalyst.