Abstract
The dihydropyridazine ring undergoes contraction to a dihydropyrrole ring to give 1-phenyl-2-benzylideneaminodihydropyrrolo[3,4-b]indol-3-ones when 1-phenyldihydropyridazino[4,5-b]indol-4-ones are treated with aromatic aldehydes under acid catalysis conditions. The reaction mechanism consists in the formation of a (3-indolyl)phenylmethyl cation, which leads to opening of the pyridazine ring and subsequent development of a bond between the carbonium center and the amide nitrogen atom.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1406–1408, October, 1976.
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Kogan, N.A., Vlasova, M.I. Isomerization of pyridazino [4,5-b] indoles to pyrrolo [3,4-b] indoles. Chem Heterocycl Compd 12, 1162–1165 (1976). https://doi.org/10.1007/BF00945606
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DOI: https://doi.org/10.1007/BF00945606