Synthesis of Polyheterocyclic Ring Systems Included Triazolo[1, 5-a]Pyrimidine as Antioxidant Agents. (22nd April 2022)

• Record Type: Journal Article
• Authors: Bayazeed, Abrar A.; Alnoman, Rua B.
• Is Part Of: Polycyclic aromatic compounds. Volume 42:Number 3(2022)
• Page Start: 735
• Page End: 748
• Publication Date: 2022-04-22
• Subjects: ABTS -- aminotetrazole -- antioxidant -- DMF-DMA -- hydrazines -- triazolo[1, 5-a]pyrimidine; Polycyclic aromatic compounds -- Periodicals; 547
• DOI: 10.1080/10406638.2020.1750042
• Languages: English
• ISSNs: 1040-6638

Abstract

Abstract: The highly versatile 6-cyano-5-oxo-3, 5-dihydro-[1, 2, 4]triazolo[1, 5- a ]pyrimidine (6 ) has been synthesized and utilized as a building block for the design of new tricyclic and tetracyclic ring systems incorporating the triazolo[1, 5- a ]pyrimidine skeleton. The synthetic strategy for the construction of novel tricyclic classes, pyrazolo[4, 3- e ]triazolo[1, 5- a ]pyrimidines 7 –8, pyrido[3, 4- e ]triazolo[1, 5- a ]pyrimidines 9 –10, and pyrano[3, 4- e ]triazolo[1, 5- a ]pyrimidines 12 –14, based on reactions of the precursor 6 with hydrazines, activated nitriles, β-diketones, β-ketonitriles, and pyrazolones. The tetra-heterocyclic systems in which the pyrimido-[1, 2, 4]triazolo[1, 5- a ]pyrimidine fused with different rings such as tetrazole, triazole, imidazole, and/or pyrazole were synthesized through the heterocyclization of the precursor 6 with various α-aminoazoles (namely; 5-amino-1 H -tetrazole, 3-amino-4 H -1, 2, 4-triazole, 2-aminobenzimidazole, 5-amino-3-methyl-1 H -pyrazole, and/or 5-amino-4-arylazo-pyrazoles). The newly synthesized polyheterocyclic ring systems were characterized by spectroscopic evidence, using IR, 1 H and 13C NMR, and mass analyses. The triazolo[1, 5- a ]pyrimidine-based compounds were assayed for antioxidant properties by the ABTS technique to identify the tricyclic pyrano[3, 4- e ]triazolo[1, 5- a ]pyrimidine compounds 12a and 12b that exhibit the best antioxidant activity with percent inhibition (86.07% and 85.29%).