Abstract Reactions of 4-ethoxycarbonylamino-1H-1, 5-benzodiazepine-3-carbonitrile (2) with aliphatic primary amines gave 1-substituted 4-(2-aminoanilino) pyrimidin-2 (1H)-one-5- carbonitriles 3. Analogous reactions of 2 with aromatic primary amines afforded 2-(2′- anilino-1′-cyanovinyl) benzimidazoles 5 and 6. Upon treatment with triethylamine, 3 underwent intramolecular cyclization to give 3-substituted 5-aminopyrimidino [4, 5-b]-[1, 5] ...