Department of Chemistry and Institute of Chemical Biology and Drug Discovery, Stony Brook University, Stony Brook, NY, 11794, USA.
Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
Angew Chem Int Ed Engl. 2018 Oct 15;57(42):13795-13799. doi: 10.1002/anie.201808495. Epub 2018 Sep 20.
The trifluoromethoxy (OCF ) radical is of great importance in organic chemistry. Yet, the catalytic and selective generation of this radical at room temperature and pressure remains a longstanding challenge. Herein, the design and development of a redox-active cationic reagent (1) that enables the formation of the OCF radical in a controllable, selective, and catalytic fashion under visible-light photocatalytic conditions is reported. More importantly, the reagent allows catalytic, intermolecular C-H trifluoromethoxylation of a broad array of (hetero)arenes and biorelevant compounds. Experimental and computational studies suggest single electron transfer (SET) from excited photoredox catalysts to 1 resulting in exclusive liberation of the OCF radical. Addition of this radical to (hetero)arenes gives trifluoromethoxylated cyclohexadienyl radicals that are oxidized and deprotonated to afford the products of trifluoromethoxylation.
三氟甲氧基（OCF）自由基在有机化学中具有重要意义。然而，在室温常压下催化且选择性地生成这种自由基仍然是一个长期存在的挑战。在此，报告了一种氧化还原活性的阳离子试剂（1）的设计和开发，该试剂可在可见光光催化条件下可控、选择性和催化地形成 OCF 自由基。更重要的是，该试剂允许广泛的（杂）芳基和生物相关化合物的催化、分子间 C-H 三氟甲氧基化。实验和计算研究表明，从激发的光氧化还原催化剂到 1 的单电子转移（SET）导致 OCF 自由基的专一地释放。将该自由基加成到（杂）芳基上得到三氟甲氧基环己二烯基自由基，该自由基被氧化并去质子化以得到三氟甲氧基化的产物。
