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.