Synthesis and Antioxidant Activity of 1,2,4-Triazole linked Thieno[2,3- d]pyrimidine Derivatives

A series of Schiff bases derivatives novel 3-(4-substitutedbenzylideneamino-5-mercapto-4H-[1,2,4]triazol-3- ylmethyl)-5,6,7,8-tetrahydro-3H-benzo[4,5]thieno[2,3-d]pyrimidin-4-one derivatives (7a–k) have been synthesized from compound (1) through a multi step reaction. The key intermediate (6) on condensation with various suitable aldehydes in the presence of sulfuric acid afforded a series of title compounds (7a–k). The structures of all newly synthesized compounds were established on the basis of their elemental analysis, IR, 1H-NMR, 13C-NMR and MS spectral data. All these novel compounds were screened for their in vitro antioxidant activity by employing DPPH, hydrogen peroxide, and nitric oxide radical scavenging assays. The compounds 7c, 7j, 7k, 7e and 7b showed significant radical savenging due to the presence of electron-withdrawing groups.