Abstract
Treatment of 2-cyclopropylazobenzenes with concentrated sulfuric acid affords the intramolecular N- and C-alkylation products. Treatment of azobenzenes with trifluoroacetic acid results in quantitative rearrangement to arylindazoles via the intermediate formation of acid-stable indazolium ions. It is suggested that the formation of indazolium ions in trifluoroacetic acid results from the synchronous opening of the cyclopropane ring and stabilization of the developing carbocation by an internal nucleophile (the azo-group).
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1063–1068, August, 1987.
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Fedotov, A.N., Shishkina, I.N., Kutateladze, T.G. et al. Protic acid-induced intramolecular reactions of 2-cyclopropylazobenzenes. Chem Heterocycl Compd 23, 849–854 (1987). https://doi.org/10.1007/BF00473455
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DOI: https://doi.org/10.1007/BF00473455