Synthesis and Electrophilic Substitutions of Novel Pyrazolo[1,5-c]-1,2,4-triazolo[4,3-a]pyrimidines

Abstract

5-Aryl-7-hydrazino-2-phenylpyrazolo[1,5-c]pyrimidines 1 were used as precursors for the preparation of a new series of 5-aryl-8-phenylpyrazolo[1,5-c]-1,2,4- triazolo[4,3-a]pyrimidines 2. The reactions of 2 with certain electrophilic reagents gave the respective 6-substituted derivatives 3-5 rather than the 7-isomeric products. Formylation of the key compounds 1 with ethyl formate yielded the formyl derivatives 6. Furthermore, boiling of compounds 1 with acetic acid afforded 7-acetylhydrazino-5-aryl-2-phenylpyrazolo[1,5-c]pyrimidines 7. Bromination of 7 yielded the dibromo- derivatives 8, while their iodination and nitration gave the monosubstituted derivatives 9 and 10, respectively. Also, treatment of 1 with boiling acetic anhydride yielded the triacetyl derivatives 11. The structure of synthesized products was confirmed by elemental analyses, IR, 1H NMR and MS spectra.

Synthesis and Antibacterial Activities of Novel 2,5-Diphenylindolo[2,3-e] Pyrazolo[1',5':3",4"]pyrimido[2",1"-c] [1,2,4]triazines

“…Encouraged by the above observations and in continuation of our work for the syntheses of heterocyclic compounds from hydrazino heterocycles [27,28,29,30,31,32], a new series of 3-{2-(2,5-diphenyl- pyrazolo[1,5- c ]pyrimidin-7-yl)hydrazono}indolin-2-ones and 2,5-diphenylindolo[2,3- e ]pyrazolo- [1',5':3",4"]pyrimido[2",1"- c ][1,2,4]triazines were synthesized, with a view to explore the possibility of achieving better biological activities.…”