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Nagamatsu, T. and Fujita, T. (1999) Facile and General Syntheses of 3- and/or 5-Substituted 7H-pyrazolo[4,3-e]-1,2,4-triazolo[4,3-c]pyrimidines as a New Class of Potential Xanthine Oxidase Inhibitors. Chemical Communications, 16, 1461.

has been cited by the following article:

• TITLE: Utility of Styrylpyrazoloformimidate in the Synthesis of Fused Heterocyclic Compounds

  AUTHORS: Hamdi M. Hassaneen, Zakaria Ahmed Gomaa

  KEYWORDS: (Z)-N'-Phenylcinnamohydrazonoyl Chloride, (E)-5-Amino-1-Phenyl-3-Styryl-1H-Pyrazole-4-Carbonitrile, Formimidate, Dimroth Rearrangement

  JOURNAL NAME: International Journal of Organic Chemistry, Vol.5 No.4, November 24, 2015

  ABSTRACT: Refluxing of (E)-5-amino-1-phenyl-3-styryl-1H-pyrazole-4-carbonitrile 2 with triethylor-thoformate in acetic anhydride afforded the corresponding formimidate 3. Treatment of 3 with hydrazine hydrate in ethanol afforded amino imino compound 4. Reaction of 4 with diethyl dicarbonate at reflux gave (E)-7-phenyl-9-styryl-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine 7. Refluxing of 4 with hydrazine hydrate afforded (E)-4-hydrazinyl-1-phenyl-3-styryl-1H-pyrazolo[3,4-d] pyrimidine 8. Treatment of the latter compound 8 with aldehydes in boiling ethanol in the presence of acetic acid afforded the corresponding hydrazone 10. Oxidative cyclization of the hydrazone 10 led to the formation of pyrazolo[4,3-e][1,2,4]triazolo[4,3-c]pyrimidine 11. The latter products re-arranged to pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidines 13. The structures of the new products were established on the basis of elemental analysis and spectral data.