Imidazo[1,2-a]benzimidazole derivatives

3-Amino derivatives of 9-alkyl(benzyl)-2-arylimidazo1,2-a]benzimidazoles, obtained by the reduction of the appropriate 3-nitro(nitroso) derivatives, are extremely unstable, and the imidazole ring opens readily resulting in conversion to 2-(-carboxybenzylamino)benzimidazoles. The reaction apparently proceeds through the intermediate formation of 2-(-cyanobenzylamino)benzimidazole, which is a tautomeric form of the 3-amino compound and can react as such to form 3-acylamino derivatives and anils. If there is a methyl group in the 3-position of the ring, the amine is quite stable and can be isolated in free form.See 1] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 673–677, May, 1971.