PIDA-mediated intramolecular oxidative C–N bond formation for the direct synthesis of quinoxalines from enaminones

Abstract

A intramolecular oxidative C(sp²)–N bond formation mediated by hypervalent iodine(III) to obtain quinoxalines from readily available N-(2-acetaminophenyl)enaminones was developed. A tandem process involving PIDA-mediated intramolecular condensation cyclization and a subsequent elimination was postulated, which was highly efficient and metal-free under mild conditions. Moreover, flexible structural modifications of quinoxalines bearing carbonyl groups are of interest for further transformations as building blocks in organic synthesis.