Electrochemical Direct Formyloxylation of Benzylic C(sp3)-H with DMF

Herein, the first electrochemical strategy for direct acyloxylation of benzylic C(sp3)-H with amides is described. The method features transition metal-and oxidant-free conditions with H2 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(sp3)-H functionalization and the process of amide C-N bond breaking.

Automated summary

Here, we report the first electrochemical strategy for direct acyloxylation of benzylic C(sp3)-H with amides. The method offers transition metal and oxidant-free conditions with H2 evolution, excellent tolerance towards various functional groups, and high yields up to 82% in an operation-friendly undivided cell. Mechanistic experiments confirm the involvement of radicals and the breaking of the amide C-N bond.