Reaction of pyrrolo[1,2-a]pyrazinetriones with o-phenylenediamine. Synthesis of angular benzo[b]pyrazino[1′,2′: 1,2]pyrrolo[2,3-e][1,4]diazepines

4-Acyl-substituted 1H-pyrrole-2,3-diones fused through the N–C bond to nitrogen heterocycles are known to react with o-phenylenediamine along three pathways. 3-Aroyland 3-heteroaroylpyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones (1H-pyrrole-2,3-diones fused through the N–C bond to a 1,4-benzoxazine fragment) react with o-phenylenediamine via initial addition of the amino group to C, opening of the oxazine and pyrrole rings, and subsequent heterocyclization to quinoxalin-2-one derivatives [1, 2]. 3-Aroylpyrrolo[1,2-a]quinoxaline-1,2,4-triones (1H-pyrrole-2,3-diones fused through the N–C bond to a quinoxaline fragment) also react with o-phenylenediamine via initial addition of the amino group to C, but next follows intramolecular cyclization involving the aroyl carbonyl group with formation of substituted benzo[b]pyrrolo[2,3-e][1,4]diazepines [3]. The first step in the reaction of 3-pivaloylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones with o-phenylenediamine is addition of the amino group in the latter to C, and subsequent opening of the pyrrole ring and heterocyclization lead to 3-(quinoxalin-2-ylmethyl)quinoxalin-2-one derivatives [4]. We previously synthesized new hetareno[e]pyrrole2,3-diones, 8-aroyl-3,4-dihydropyrrolo[1,2-a]pyrazine1,6,7(2H)-triones [5] (1H-pyrrole-2,3-diones fused through the N–C bond to a pyrazine fragment). In the present communication we report their reaction with o-phenylenediamine.