Tert-Butyl Hypochlorite Induced Cyclization of Ethyl 2-(N-Aryl­carbamoyl)-2-iminoacetates

Abstract

Ethyl 2-(N-arylcarbamoyl)-2-iminoacetates can be transformed into the corresponding quinoxalin-2-ones in high yield by using the oxidation system of tert-butyl hypochlorite, tetrabutylammonium iodide and tetrabutylammonium chloride. Oxygen exhibits a beneficial effect on the reaction. The reaction is proposed to follow an iminyl radical cyclization mechanism where azaspirocyclohexadienylperoxyl radical is formed as a key intermediate. The quinoxalin-2-one is derived from the azaspirocyclohexadienylperoxyl radical via concurrent oxygen extrusion and rearrangement.