Aromaticity and aminopyrroles: Desmotropy and solution tautomerism of 1 H-pyrrol-3-aminium and 1 H-pyrrol-3(2 H)-iminium cation: A stable σ-complex

Michael De Rosa, David Arnold

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Abstract

Protonation of 3-aminopyrrole at C-2 gave the σ-complex 1H-pyrrol-3(2H)-iminium cation, whereas protonation at the exoamino group gave its 1H-pyrrol-3-aminium tautomer. Both tautomers were isolated as their respective tetrakis(pentafluorophenyl)borate salt, an example of desmotropy. In solution, the NH3-tautomer was favored in hydrogen-bonding solvents and the CH2-tautomer in CH2Cl2. A combination of effects on the aromaticity of the aminopyrrole ring increased the relative stability of the σ-complexes (conjugate acids) such that they can be readily observed or isolated.

Original languageEnglish (US)
Pages (from-to)1107-1112
Number of pages6
JournalJournal of Organic Chemistry
Volume78
Issue number3
DOIs
Publication statusPublished - Feb 1 2013

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All Science Journal Classification (ASJC) codes

  • Organic Chemistry

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