Synthesis and Electrophilic Substitutions of Novel Pyrazolo1,5-c-1,2,4-triazolo4,3-apyrimidinesReportar como inadecuado




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Chemistry Department, Faculty of Science, Alexandria University, Ibrahimia P.O. Box 426, Alexandria 21321, Egypt





Abstract 5-Aryl-7-hydrazino-2-phenylpyrazolo1,5-cpyrimidines 1 were used as precursors for the preparation of a new series of 5-aryl-8-phenylpyrazolo1,5-c-1,2,4- triazolo4,3-apyrimidines 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-phenylpyrazolo1,5-cpyrimidines 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.

Keywords: pyrazolo1,5-c-1,2,4-triazolo4,3-apyrimidines; synthesis; electrophilic substitution reactions; dehydrative cyclization pyrazolo1,5-c-1,2,4-triazolo4,3-apyrimidines; synthesis; electrophilic substitution reactions; dehydrative cyclization





Autor: Kamal F.M. Atta

Fuente: http://mdpi.com/



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