Abstract
The effect of protonation of the oxygen atom of the carbonyl group and the carbon atom of the pyrrole ring on the 13C chemical shifts in a series of 3- and 5-formyl-, 3-acetyl-, and 3-carbethoxypyrroles was studied. The structures of the conjugate acids of the 5-carbethoxypyrroles was established on the basis of measurement of the 1H and 13C NMR spectra. It is shown that protonation of the 5-carbethoxypyr roles occurs at the ring 5-C atom in 28–35 N H2SO4. The effect of structural factors and the acidity of the medium on the relative stabilities of the CH conjugate acids of the investigated compounds is examined.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 485–492, April, 1979.
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Struchkova, M.I., Dvoryantseva, G.G. & Evstigneeva, R.P. 13C NMR spectra of the bases and conjugate acids of 3- and 5-formyl-,acetyl-, and carbethoxypyrroles. Chem Heterocycl Compd 15, 394–400 (1979). https://doi.org/10.1007/BF00471772
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DOI: https://doi.org/10.1007/BF00471772