Preparation-of stable nitroxyl radicals with an amino group at the ?-carbon atom of the radical center by oxidative amination of 4H-imidazole N-oxides

Abstract

1. Upon oxidation of 1-hydroxy-4R21-2R2-5,5-dimethyl-3-imidazoline-3-oxides or the corresponding N,N-dioxides of 4H-imidazole with lead dioxide in saturated alcoholic solutions of amines there are formed stable nitronylnitroxyl and nitroxyl radicals of the imidazoline-N-oxide series, which contain a primary or secondary amino group at the α-carbon atom of the radical center. 2. The ratio of reaction products depends on the nature of the substituents: donating R1 and accepting R2 favor formation of nitroxyl radicals of 3-imidazoline-3-oxide. 3. Upon oxidation of N-oxides of 4H-imidazole in alcoholic solutions of amines iminonitroxyl radicals are formed which contain an amino group at the central carbon atom.