Abstract
The reaction of 4-nitro-o-phenylenediamine (I) with acetoacetic ester at room temperature under acid catalysis gives ethyl 3-(2-amino-5-nitrophenylamino)crotonate (II), which is readily cyclized to 7-nitro-4-methyl-2,3-dihydro-1H-1,5-benzo-2-diazepinone (III) on heating with alkaline agents. The reaction of I with acetoacetic ester in refluxing xylene gives isomeric 8-nitro-4-methyl-2,5-dihydro-1H-1,5-benzo-2-diazepinone (IVa) or 8-nitro-4-methyl-2,3-dihydro-1H-1,5-benzo-2-diazepinone (IVb), which are readily interconverted. The synthesis of IV is complicated by the side formation of 5-nitro-2-methylbenzimidazole (V) and thermal rearrangement of IVa and IVb to 5-nitro-1-isopropenylbenzimidazolone (VI). 6-Nitro-1-isopropenylbenzimidazolone (VII) is similarly obtained on heating III.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 696–699, May, 1972.
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Kost, A.N., Solomko, Z.F., Budylin, V.A. et al. Synthesis of 5(and 6)-nitro-4-methyl-2,3-dihydro-1h-1,5-benzo-2-diazepinones. Chem Heterocycl Compd 8, 632–635 (1972). https://doi.org/10.1007/BF00488164
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DOI: https://doi.org/10.1007/BF00488164