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Chemistry of Heterocyclic Compounds

, Volume 28, Issue 12, pp 1461–1467 | Cite as

Ring contraction of thia(seleno)diazine rings into pyrazoles in the reaction of 3-aryl-10-methyl-2H-1,3,4-thia(seleno)diazino[3, 2-a]benzimidazolium salts with bases

  • T. A. Kuz'menko
  • V. V. Kuz'menko
  • O. V. Kryshtalyuk
  • A. F. Pozharskii
Article

Abstract

Reaction of 3-aryl-10-methyl-2H-1,3,4-thiadiazino[3,2-a]benzimidazolium salts with triethylamine led to ring contraction of the thiadiazine ring to a pyrazole ring with the formation of a mixture of derivatives of 3-mercaptopyrazolobenzimidazole and di(pyrazolo[1,5-a]benzimidazolyl-3) disulfide. The disulfides were formed exclusively when these salts react with ethanolic alkali. The reaction with potassium carbonate in acetic anhydridegave3-acetylthiopyrazolo[1,5- a]benzimidazoles. 2-Aryl-4- alkylpyrazolo[1, 5- a]benzimidazoles were formed by heating thiadiazino[3,2-a]benzimidazolium salts in formamide and by treating selenodiazino[3,2-a]benzimidazolium salts with potassium carbonate in acetic anhydride.

Keywords

Acetic Potassium Organic Chemistry Disulfide Anhydride 
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

© Plenum Publishing Corporation 1993

Authors and Affiliations

  • T. A. Kuz'menko
    • 1
  • V. V. Kuz'menko
    • 1
  • O. V. Kryshtalyuk
    • 1
  • A. F. Pozharskii
    • 1
  1. 1.Physical and Organic Chemistry Research InstituteRostov State UniversityRostov-on-Don

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