Issue 8, 2022

Direct C(sp3)–H difluoromethylation via radical–radical cross-coupling by visible-light photoredox catalysis

Abstract

Herein, a radical–radical cross-coupling strategy for direct difluoromethylation of the C(sp3)–H bond is reported. This transformation was readily accomplished under transition metal-free photoredox catalysis in the presence of 3 mol% of an organic photocatalyst, allowing the direct difluoromethylation of C(sp3)–H of a wide variety of 1,4-dihydroquinoxalin-2-ones in good yields under mild reaction conditions. Moreover, various 3-difluoromethyl quinoxalin-2-ones were also easily furnished in a one-pot manner through this radical difluoromethylation protocol. Mechanistic studies clearly reveal that the radical–radical cross-coupling between a difluoromethyl radical and a C(sp3) radical is responsible for this transformation. To the best of our knowledge, this is the first example of radical–radical cross-coupling difluoromethylation of the C(sp3)–H bond, which not only provides a promising strategy for a straightforward installation of a CF2H group at a C(sp3) center but would also promote the development of other new fluorination and fluoroalkylation methods.

Graphical abstract: Direct C(sp3)–H difluoromethylation via radical–radical cross-coupling by visible-light photoredox catalysis

Supplementary files

Article information

Article type
Research Article
Submitted
11 feb 2022
Accepted
03 mar 2022
First published
03 mar 2022

Org. Chem. Front., 2022,9, 2141-2148

Direct C(sp3)–H difluoromethylation via radical–radical cross-coupling by visible-light photoredox catalysis

W. Xiong, W. Qin, Y. Zhao, K. Fu and G. Liu, Org. Chem. Front., 2022, 9, 2141 DOI: 10.1039/D2QO00192F

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