Alumina supported potassium permanganate: An efficient reagent for chemoselective dehydrogenation of 2-imidazolines under mild conditions

Abstract

An efficient method for the oxidation of 2-imidazolines to their corresponding imidazoles using KMnO 4/Al 2O 3 under very mild reaction conditions is reported. Selective oxidation of 2-alkylimidazolines was also performed in the presence of 2-arylimidazolines and other functional groups such as sulfide, ether, aldehyde, acetal and THP ether. Potassium permanganate supported on alumina was found to be an efficient reagent system for dehydrogenation of 2-imidazolines to imidazoles under mild conditions at room temperature. Selective oxidation of 2-alkylimidazolines in the presence of 2-arylimidazolines was achieved using this reagent system. 2-Imidazolines were also selectively converted to their corresponding imidazoles in the presence of other oxidizable functional groups such as sulfide, ether, aldehyde, acetal and THP ether. The oxidation procedure described here is easy to carry out and does not require strict reaction conditions. © 2004 Elsevier Ltd. All rights reserved.