The reaction of 4-(2R-1-chloro-2-oxoethylidene) -substituted imidazolidine-1-oxyl with sodium azide gives monoimines of alpha -diketones, derivatives of 3-imidazoline nitroxides. Reactions of these products with nitrogen binucleophiles were used to prepare various heterocyclic compounds containing an imidazoline nitroxide moiety.