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Functionalized 2,5-Dipyridinylpyrroles by Electrochemical Reduction of 3,6-Dipyridinylpyridazine Precursors

  1. Hicham Bakkali1,2,
  2. Cécile Marie1,2,
  3. Akarim Ly3,
  4. Christine Thobie-Gautier1,2,
  5. Jérôme Graton1,2,
  6. Muriel Pipelier1,2,
  7. Stéphane Sengmany4,
  8. Eric Léonel4,
  9. Jean-Yves Nédélec4,
  10. Michel Evain5,
  11. Didier Dubreuil1,2

Article first published online: 13 MAR 2008

DOI: 10.1002/ejoc.200701115

Issue

European Journal of Organic Chemistry

European Journal of Organic Chemistry

Volume 2008, Issue 12, pages 2156–2166, April 2008

Additional Information

How to Cite

Bakkali, H., Marie, C., Ly, A., Thobie-Gautier, C., Graton, J., Pipelier, M., Sengmany, S., Léonel, E., Nédélec, J.-Y., Evain, M. and Dubreuil, D. (2008), Functionalized 2,5-Dipyridinylpyrroles by Electrochemical Reduction of 3,6-Dipyridinylpyridazine Precursors. European Journal of Organic Chemistry, 2008: 2156–2166. doi: 10.1002/ejoc.200701115

Author Information

  1. 1

    Université de Nantes, CEISAM, Chimie Et Interdisciplinarité, Synthèse, Analyse, Modélisation, UFR des Sciences et des Techniques, 2 rue de la Houssinière, B. P. 92208, 44322 Nantes Cedex 3, France

  2. 2

    CNRS, UMR CNRS 6230 2 rue de la Houssinière, B. P. 92208, 44322 Nantes Cedex 3, France

  3. 3

    Département de Génie Chimique, Université de Conakry, Guinea

  4. 4

    Electrochimie et Synthèse Organique, Institut de Chimie et des Matériaux Paris-Est UMR 7182 – CNRS, Université Paris 12, 2 rue Henri-Dunant, 94320 Thiais, France

  5. 5

    Université de Nantes, Nantes Atlantique Universités, CNRS, Faculté des Sciences et des Techniques, Institut des Matériaux Jean Rouxel, UMR CNRS 6502, 2 rue de la Houssinière, B. P. 92208, 44322 Nantes Cedex 3, France

Publication History

  1. Issue published online: 2 APR 2008
  2. Article first published online: 13 MAR 2008
  3. Manuscript Received: 26 NOV 2007

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Keywords:

  • Nitrogen heterocycles;
  • Ring contraction;
  • Electrochemistry;
  • Reduction

Graphical Abstract

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The ring contraction of 3,6-dipyridinylpyridazines into the corresponding pyrroles was investigated following an electrochemical procedure. The mechanism involveda four-electron, four-proton process and the formation of an 1,2-dihydropyridazine as a key intermediate.

Abstract

The ring contraction of pyridinylpyridazine derivatives into the corresponding pyrroles by electrochemical reduction was studied, and the influence of the substituents of the pyridazine precursors on the process is discussed. Cyclic voltammetry studies underlines the electron-withdrawing or -donating effect of the substituent on the pyridazine ring, which determines the reaction pathway of their preparative electrolysis. The ring-contraction process, with extrusion of nitrogen, proceeds by two subsequent two-electron, two-proton processes via a 1,2-dihydropyridazine intermediate. The latter can either rearrange into an isolable 1,4-dihydropyridazine or undergo formation of pyrroles by disproportionation or by a second electrochemical reduction involving two-electrons and two protons. X-ray structure, fluorescence spectra, and conformational analysis of pyridinylpyrrole sequences supported this study. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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