Synthesis of novel imidazo[1,2‐ a ]pyrrolo[2,1‐ c ][1,4]benzodiazepines and pyrimido[1,2‐ a ]pyrrolo[2,1‐ c ][1,4]benzodiazepines

Several 1 1‐amino‐5 H ‐pyrrolo[2,1‐ c ][1,4]benzodiazepines have been used as starting material to prepare a number of derivatives of 9 H ‐imidazo[1,2‐ a ]pyrrolo[2,1‐ c ][1,4]benzodiazepines and 10 H ‐pyrimido[1,2‐ a ]pyrrolo[2,1‐ c ][1,4]benzodiazepines. The imidazole nucleus was built by reaction of amidines with ethyl bromopyruvate or aminoacetaldehyde dimethylacetal. Several derivatives of imidazo[1,2‐ a ]pyrrolo[2,1‐ c ][1,4]benzodiazepine have been prepared by formylation of the pyrrole ring followed by formation of thioamides. Condensation of 11‐amino‐5 H ‐pyrrolo[2,1‐ c ][1,4]benzodiazepines with diethyl ethoxymethylenemalonate afforded intermediate diesters which were transformed into the corresponding 10 H ‐pyrimido[1,2‐ a ]pyrrolo[2,1‐ c ]‐benzodiazepines.