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.
Highlights
The chemistry of hydrazonoyl halides has attracted the interest of many research groups as they have proved to be useful organic synthesis [1]-[10]
In continuation of our long standing interest for the utility of nitrilimines derived from hydrazonoyl halides in the synthesis of heterocycles [11]-[14], we are interested in (Z)-N'-phenylcinnamohydrazonoyl chloride 1 to study the effect of C=C double bond on the cycloaddition reactions [15]-[17]
Compound (E)-5-amino-1-phenyl-3-styryl-1H-pyrazole-4-carbonitrile 2 was prepared from our laboratory via reaction of (Z)-N'-phenylcinnamohydrazonoyl chloride 1 with malononitrile in ethanolic sodium ethoxide solution (Scheme 1) [21]
Summary
The chemistry of hydrazonoyl halides has attracted the interest of many research groups as they have proved to be useful organic synthesis [1]-[10]. 4-((Z)-2-Benzylidenehydrazinyl)-1-phenyl-3-((E)-styryl)-1H-pyrazolo[3,4-d]pyrimidine 10a: Yellow crystals; m.p. 188 ̊C - 189 ̊C (acetonitrile); yield (87%); IR (KBr): υ = 3205 (NH) cm−1, 1H NMR (DMSO-d6): δ = 7.15 - 8.58 (m, 19H, Ar H), 12.04 (s, 1H, NH).
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