Hetrocycles from nitrile imines. Part III. Substituent effect on ring-chain tautomerism of 1,2,3,4-tetrahydro-s-tetrazines

Mustafa M. El-Abadelah, Ahmad Q. Hussein, Haythem A. Saadeh

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

Selected series of 6-substituted 4-aryl-3-heteroaryl-1-methyl-1,2,3,4-tetrahydro-s-tetrazines (V;1-12) were synthesized via direct interaction between appropriate nitrile imine and model methylhydrazones. The extent of "ring-chain" tautomerism, as evidenced from nmr spectral data of V, is dependent on the nature of substituents at N-4, C-3, and C-6. The results reveal that: (i) The concentration of the cyclic tautomer tends to decrease as the basicity of the arylated N-4 decreases, (ii) For C-3 substituents, the cyclic tautomer ratio decreases in the order: phenyl > pyridyl > furyl > thienyl. (iii) For C-6 substituents, the cyclic ratio decreases in the order: C6H5> CO2Me > COMe. These trends are interpreted in terms of conjugative and electronic effects.

Original languageEnglish
Pages (from-to)1063-1079
Number of pages17
JournalHeterocycles
Volume32
Issue number6
DOIs
Publication statusPublished - Jun 1 1991
Externally publishedYes

ASJC Scopus subject areas

  • Analytical Chemistry
  • Pharmacology
  • Organic Chemistry

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