Synthesis of substituted 4H-imidazo[5,1-b]benzimidazoles

4-Methyl-1-phenylimidazo[5,1-b]benzimidazole (III) has been synthesized. It has been shown that 1,4-dimethylimidazo[5,1-b]benzimidazole (I) and III readily undergo acetylation and nitrosation at position 3. The reaction of I and III with formalin, like the Mannich reaction, leads to the formation of methylenebis derivatives. The bromination of III with N-bromosuccinimide forms the 3-bromo derivative of III (X).For part IV, see [1].