Synthesis, antibacterial activity and cytotoxicity of new fused pyrazolo[1,5-a]pyrimidine and pyrazolo[5,1-c][1,2,4]triazine derivatives from new 5-aminopyrazoles
Al-Adiwish, Wedad M. and Mohamed Tahir, Mohamed Ibrahim and Adnan, Siti Noor Adnalizawati and Hashim, Siti Farah and Ibrahim, Nazlina and Yaacob, W. A. (2013) Synthesis, antibacterial activity and cytotoxicity of new fused pyrazolo[1,5-a]pyrimidine and pyrazolo[5,1-c][1,2,4]triazine derivatives from new 5-aminopyrazoles. European Journal of Medicinal Chemistry, 64 . pp. 464-476. ISSN 0223-5234
New 5-aminopyrazoles 2a–c were prepared in high yields from the reaction of known α,α-dicyanoketene-N,S-acetals 1a–c with hydrazine hydrate under reflux in ethanol. These compounds were utilized as intermediates to synthesize pyrazolo[1,5-a]-pyrimidines 3a–c, 4a–d, 5a–c, and 6a–c, as well as pyrazolo[5,1-c][1,2,4]triazines 7a–c and 8a–c, by the reaction of 2-[bis(methylthio)methylene]malononitrile, α,α-dicyanoketene-N,S-acetals 1a–b, acetylacetone, acetoacetanilide as well as acetylacetone, and malononitrile, respectively. Furthermore, cyclization of 2a–c with pentan-2,5-dione yielded the corresponding 5-pyrrolylpyrazoles 9a–c. Moreover, fusion of 2a–c with acetic anhydride resulted in the corresponding 1-acetyl-1H-pyrazoles 10a–c. The antibacterial activity and cytotoxicity against Vero cells of several selected compounds are also reported.
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