Synthesis of a new compound family, 1-aryl-3H-pyrrolo[2,1-d][1,2,5]triazepin-4(5H)-ones

Representatives of a new family, 1-aryl-3H-pyrrolo[2,1-d][1,2,5]triazepin-4(5H)-ones have been synthesized at our laboratory as bioisosters of biologically active 1-aryl-2,3-benzodiazepine-4-ones. The efficient synthetic route described applies the synthesis of 2-(2-aroylpyrrol-1-yl)acyl hydrazides followed by ring closure under acidic conditions. The N(3)-unsubstituted title compounds thus obtained can optionally be N-alkylated rendering the preparation of variously substituted derivatives possible. Scope and limitations of the new protocol and some interesting side reactions are also discussed in detail.