Synthesis of Some Pyrazolo[1,5-A]Pyrimidine Derivatives Bearing Carbonitrile, Amidoxime, Carboxamide And Oxadiazole Substituents Using Commercially Available Reagents

Alqadhi, Mustafa Abdosalam; Allam, Heba; Fahim, Samar Hashem; Yahya, Tawfeek A.A.; Ragab, Fatmaa A.

doi:10.21608/ejchem.2023.231631.8493

Synthesis of Some Pyrazolo[1,5-A]Pyrimidine Derivatives Bearing Carbonitrile, Amidoxime, Carboxamide And Oxadiazole Substituents Using Commercially Available Reagents

Document Type : Original Article

Authors

¹ Department of Medicinal Chemistry, Faculty of Pharmacy, Sana'a University, P.O. Box, 18084, Sana'a, Yemen

² Faculty of Pharmacy, Cairo University

³ faculty of pharmacy Cairo university

⁴ Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Cairo University

10.21608/ejchem.2023.231631.8493

Abstract

Herein we report the synthesis of some new pyrazolo[1,5-a]pyrimidine derivatives. 7-(Aryl)-2-methyl-pyrazolo[1,5-a]pyrimidine-3-carbonitrile derivatives 9a-e which were synthesized by the condensation reaction of the amino pyrazole 3 with acetylacetone 4 or with the arylpropenones (enaminones) 8a-e in acetic acid. The reaction of the carbonitrile derivative 9e with hydroxylamine in presence of sodium acetate afforded the corresponding amidoxime derivative 10. Additionally, cyclization of the amidoxime 10 to the corresponding methyl- and phenyl- 1,2,4-oxadiazoles, 11a and 11b, was accomplished by heating it with acetic-anhydride or benzoyl chloride in pyridine. On the other hand, the cyano group present in 2-methyl-7-(thiophen-2-yl)pyrazolo[1,5-a]pyrimidine-3-carbonitrile 9e was partially hydrolyzed with sulphuric acid to afford the carboxamide 12. Based on their spectral information, the structures of the newly synthesized chemical derivatives were determined.

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