Synthesis and study of indolo[2,3-b]quinoxaline derivatives

The corresponding indolo[2,3-b]quinoxalines and spiro(benzimidazoline-2,3-indoline)-2-ones are formed in the reaction of 2,5-dibutoxy-o-phenylenediamine (I) with 5-nitro- and N-acetylisatin in 50–80% acetic acid, while the corresponding spiro(2H-benzimidazole-2,3-indole)-2-ones are formed additionally in the reaction of 2,5-dibutoxy- and 2,5-diheptyloxy-o-phenylenediamine with isatin and N-methylisatin. 6-Acyl and 6- and 5-alkyl derivatives were obtained as a result of acylation and alkylation of a number of 6H-indolo[2,3-b]quinoxalines; the 5-substituted compounds are formed in trace amounts. The IR and electronic spectra of the synthesized compounds were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 249–254, February, 1981.