Reduction of 4H-imidazole N-oxides with sodium borohydride

The reduction of derivatives of 4H-imidazole N-oxides with sodium borohydride leads, depending on the presence and position of an N-oxide group, to 1-hydroxyimidazoline or imidazolidine derivatives. Under the same conditions 4H-imidazole N,N-dioxides form 1,3-dihydroxyimidazolidines. The reduction of 1-hydroxy-2,4,5,5-tetramethyl-3-imidazoline 3-oxide leads to N-(3-oximino-2-methyl-2-butyl) ethylhydroxylamine. It was observed by UV spectroscopy that 1-hydroxy-2-imidazolines exist in a tautomeric equilibrium with 2-imidazoline 3-oxides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1557–1561, November, 1976.