Issue 15, 2022

Bromine-radical-induced Csp2–H difluoroalkylation of quinoxalinones and hydrazones through visible-light-promoted Csp3–Br bond homolysis

Abstract

Disclosed herein is a photosensitizer-free strategy for the direct C–H difluoroalkylation of quinoxalinones and hydrazones with bromodifluoroacylarenes via a visible-light-promoted Csp3–Br bond homolytic pathway. This new reaction provides access to difluoroalkylated quinoxaline and hydrazone derivatives with excellent substrate generality under simple, mild, green, and metal-free conditions. This process exploits the fascinating photochemical activity of bromodifluoroacylarenes in the homolysis of Csp3–Br bonds to form difluoroalkyl radicals and bromine radical species. The generated bromine radicals can mediate H abstraction/imine radical formation directly from quinoxalinones and hydrazones, which in turn quench the in situ-generated difluoroalkyl radicals to furnish the products. It is of note is that this is the first example of the application of bromine radicals in organic transformation via Csp3–Br bond homolysis induced by visible light. Moreover, the minimal structural requirements for alkyl bromide-mediated photochemical Csp3–Br bond homolysis were investigated.

Graphical abstract: Bromine-radical-induced Csp2–H difluoroalkylation of quinoxalinones and hydrazones through visible-light-promoted Csp3–Br bond homolysis

Supplementary files

Article information

Article type
Research Article
Submitted
04 May 2022
Accepted
21 Jun 2022
First published
23 Jun 2022

Org. Chem. Front., 2022,9, 4135-4145

Bromine-radical-induced Csp2–H difluoroalkylation of quinoxalinones and hydrazones through visible-light-promoted Csp3–Br bond homolysis

C. Qu, R. Huang, Y. Liu, T. Liu and G. Song, Org. Chem. Front., 2022, 9, 4135 DOI: 10.1039/D2QO00710J

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