Metal-free generation of halogen radicals using NXS/TBHP: Application in site-selective halogenation of quinoxalin-2(1H)-ones and synthesis of gem-dihaloketones

19 September 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Here we report an efficient and practical protocol for the generation of halo radicals (Br and Cl) using inexpensive and readily available NXS/TBHP reagent system at rt. The halo radicals were further utilized for the site-selective C-H bromination and chlorination of the unexplored benzo-core of quinoxalinones. This protocol offers excellent regioselectivity towards C7 position of benzo-core over readily functionalized C3 position in hetero-core of quinoxalinones under mild reaction conditions. Notably, this transformation showed good functional group compatibility and a wide substrate scope. Further, selective synthesis of gem-dihaloketones from alkynes has been accomplished using the same reagent system.

Keywords

halogenation
quinoxalin-2(1H)-ones
alkynes
gem-dihaloketones

Supplementary materials

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Title
Metal-free generation of halogen radicals using NXS/TBHP: Application in site-selective halogenation of quinoxalin-2(1H)-ones and synthesis of gem-dihaloketones
Description
Here we report an efficient and practical protocol for the generation of halo radicals (Br and Cl) using inexpensive and readily available NXS/TBHP reagent system at rt. The halo radicals were further utilized for the site-selective C-H bromination and chlorination of the unexplored benzo-core of quinoxalinones. This protocol offers excellent regioselectivity towards C7 position of benzo-core over readily functionalized C3 position in hetero-core of quinoxalinones under mild reaction conditions. Notably, this transformation showed good functional group compatibility and a wide substrate scope. Further, selective synthesis of gem-dihaloketones from alkynes has been accomplished using the same reagent system.
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