Work

NXS/TBHP as a Reagent System for Expedient Generation of Halogen Radicals: Site ‐Selective Halogenation of Quinoxalin‐2(1 H )‐ones and Conversion of Terminal Alkynes to gem ‐Dihaloketones

Year: 2025

Type: article

Abstract: We report an efficient and practical protocol for the generation of halogen (Br and Cl) radicals using inexpensive and readily available N-bromo/N-chlorosuccinimide (NXS) and t-butylhydroperoxide (TBHP) at rt. The NXS/TBHP reagent systems are demonstrated for site-selective bromination and chlorination of the benzene-core of quinoxalin-2(1H)-ones. It is shown that the reagent system permits regioselective halogenation at the C7 position of the benzene core over the readily-functionalized C3 position of quinoxalin-2(1H)-ones under mild reaction conditions. We further show that terminal alkynes can be converted to gem-dihaloketones in a facile manner by NXS/TBHP. Mechanistically, single electron transfer between TBHP and NXS leads to instantaneous formation of electrophilic halogen radicals, which attack arenes and alkynes.

Source: Chemistry - A European Journal

DOI: 10.1002/chem.202404228

Authors: Navin Yadav, Ajay Kumar Sahoo, Debarghya Sarkar, Jarugu Narasimha Moorthy

Institutions: Indian Institute of Technology Kanpur, Indian Institute of Science Education and Research Thiruvananthapuram

Language: English

Topic: Radical Photochemical Reactions

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: bronze

Funders: Indian Institute of Technology Kanpur, Science and Engineering Research Board

Award: G1269434502