One-pot protocol for the synthesis of quinoxalines from styrenes, o-phenylenediamine and benzo[c][1,2,5]thiadiazole-4,5-diamine using triiodoisocyanuric acid

Abstract

Triiodoisocyanuric acid (TICA) controlled one-pot and easy-operational protocol has been developed for the synthesis of substituted phenylquinoxalines (3a-3i) and phenyl-[1,2,5]thiadiazolo[3,4-f]quinoxaline (5a-5f) from styrenes with o-phenylenediamine and benzo[c][1,2,5]thiadiazole-4,5-diamine respectively. The reaction involves co-bromination and oxidation for the formation of an a-bromo ketone as an intermediate in the presence of triiodoisocyanuric acid, followed by condensation with the o-phenylenediamine and benzo[c][1,2,5]thiadiazole-4,5-diamine for the formation of phenylquinoxalines (3a-3i) and phenyl-[1,2,5]thiadiazolo[3,4-f]quinoxaline (5a-5f) in 55-79% yield. This protocol environmentally benign and economically viable. Substituted quinoxalines were obtained in good to excellent yields with wide substrate scope and functional-group tolerance.