New Synthetic Approach for the Preparation of Imidazole N3-Oxide

ABSTRACT A new synthetic procedure of 1-alkyl(aryl)-1H-4-methylimidazole N 3 -oxide derivatives by cyclocondensation of α-amine­oximes and orthoesters was studied. Low yields in the cyclization process were the result of predominant Z-stereoisomer around the oxime moiety of α-amineoxime reactants. Different attempts to improve these yields were assayed, mild conditions being those that produce the best results. Also, the special acidity of hydrogen-2 in the imidazole N 3 -oxide system was studied in solution by NMR spectroscopy. This property provides a convenient intermediate to access 2-substituted analogues.