Research on nitrogen containing heterocyclic compounds. XVII . Synthesis of 8 H ‐diimidazo[1,5‐ a :2′,1′‐ c ][1,4]benzodiazepine, a novel tetracyclic ring of pharmaceutical interest

The synthesis of 8 H ‐diimidazo[1,5‐ a :2′,1′‐ c ][1,4]benzodiazepine 6 , a novel nitrogen‐containing tetracyclic ring, is reported starting from 5 H ‐imidazo[2,1‐ c ][1,4]benzodiazepine 7. Reaction of this compound with nitromethane and subsequent reduction of the obtained nitromethyl derivative 8 afforded 11‐aminomethyl‐10,11‐dihydro‐5 H ‐imidazo[2,1‐ c ][1,4]benzodiazepine 9. Treatment of the latter compound with formaldehyde led to 1,2,3,3a‐tetrahydro‐8 H ‐diimidazo[1,5‐ a :2′,1′‐ c ][1,4]benzodiazepine 10 , which was then oxidized to the title compound.