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Functionalized 2,5‐Dipyridinylpyrroles by Electrochemical Reduction of 3,6‐Dipyridinylpyridazine Precursors
Author(s) -
Bakkali Hicham,
Marie Cécile,
Ly Akarim,
ThobieGautier Christine,
Graton Jérôme,
Pipelier Muriel,
Sengmany Stéphane,
Léonel Eric,
Nédélec JeanYves,
Evain Michel,
Dubreuil Didier
Publication year - 2008
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200701115
Subject(s) - chemistry , disproportionation , pyridazine , electrochemistry , cyclic voltammetry , substituent , bulk electrolysis , electrolysis , ring (chemistry) , photochemistry , medicinal chemistry , organic chemistry , electrode , catalysis , electrolyte
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)