Electrochemical Direct Formyloxylation of Benzylic C(sp<sup>3</sup>)–H with DMF
Xiaowen Wang, Yang Deng, Ruixue Li, Jin-Feng Lv, Ming-Qiu-Hao Fu, Zhi Guan, Ya‐Nan Zhao, Yan‐Hong He
Abstract
Herein, the first electrochemical strategy for direct acyloxylation of benzylic C(sp 3 )–H with amides is described. The method features transition metal- and oxidant-free conditions with H 2 evolution, the excellent functional group (including fluoro, chloro, bromo, iodo, cyano, trifluoromethyl, aldehyde, ketone, carboxyl, ester, and ether) tolerance, up to 82% yield in an operation-friendly undivided cell under the open air, and ease of scale up. A number of well-designed mechanistic experiments [e.g., radical trapping, electron paramagnetic resonance (EPR) and isotope labeling] strongly support the radical-involved process of benzylic C(sp 3 )–H functionalization and the process of amide C–N bond breaking.