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Chemistry of Heterocyclic Compounds

, Volume 29, Issue 10, pp 1163–1168 | Cite as

Imine-enamine tautomerism of dihydroazolopyrimidines 5. Steric effects and the tautomeric equilibrium for dihydro-1,2,4-triazolo[1,5-a]pyrimidines

  • S. M. Desenko
  • V. D. Orlov
  • O. V. Shishkin
  • K. É. Barykin
  • S. V. Lindeman
  • Yu. T. Struchkov
Article

Abstract

The reaction of 3-amino-1,2,4-triazole with β-dimethylaminopropiophenones or unsaturated ketones gives 5,7-disubstituted 4,7(6,7)-dihydro-1,2,4-triazolo[1,5-a]pyrimidines. An increase in the bulk of the substituent at C(7) in the bicyclic system leads to relative stabilization of the enamine tautomer of these compounds. An x-ray diffraction structural analysis of 7-tert-butyl-5-(4-methoxyphenyl)-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine showed that the introduction of a tert-butyl group into the dihydropyrimidine ring leads to significant loss of planarity of this system.

Keywords

Ketone Pyrimidine Triazole Significant Loss Relative Stabilization 
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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References

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Copyright information

© Plenum Publishing Corporation 1994

Authors and Affiliations

  • S. M. Desenko
    • 1
    • 2
  • V. D. Orlov
    • 1
    • 2
  • O. V. Shishkin
    • 1
    • 2
  • K. É. Barykin
    • 1
    • 2
  • S. V. Lindeman
    • 1
    • 2
  • Yu. T. Struchkov
    • 1
    • 2
  1. 1.Kharkov State UniversityKharkov
  2. 2.Institute of Heteroorganic CompoundsRussian Academy of SciencesMoscow

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