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Chemistry of Heterocyclic Compounds

, Volume 8, Issue 4, pp 449–453 | Cite as

Protonation of pyrrolo[1,2-a] imidazole derivatives

  • L. M. Alekseeva
  • G. G. Dvoryantseva
  • I. V. Persianova
  • Yu. N. Sheinker
  • A. A. Druzhinina
  • P. M. Kochergin
Article

Abstract

The protonation of a number of pyrrolo[1,2-a]imidazole derivatives in trifluoroacetic acid was studied by PMR spectroscopy. The 5,7-unsubstituted compounds form a mixture of two forms of cations, the structures of which correspond to the addition of a proton to the C5 and C7 atoms of the two-ring system with predominance (60–90%) of the 5-C cation. The introduction of a CH3 group into the 5 position changes the direction of protonation to favor predominant (95%) formation of the 7-C cation. The 7-methyl derivatives of pyrroloimidazole are protonated exclusively at the C5 atom. It is demonstrated that the basicity of the pyrroloimidazoles considerably surpasses the basicity of indolicine derivatives. The comparative proton-acceptor capacity of these systems is compared with the energy indexes and the reactivity indexes calculated by the simple MO LCAO method.

Keywords

Spectroscopy Organic Chemistry Imidazole Trifluoroacetic Acid Reactivity Index 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Consultants Bureau 1974

Authors and Affiliations

  • L. M. Alekseeva
    • 1
  • G. G. Dvoryantseva
    • 1
  • I. V. Persianova
    • 1
  • Yu. N. Sheinker
    • 1
  • A. A. Druzhinina
    • 1
  • P. M. Kochergin
    • 1
  1. 1.S. Ordzhonikidze All-Union Scientific-Research Institute of Pharmaceutical ChemistryMoscow

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