A straightforward and effective strategy for the synthesis of novel 7-cyano- 4-imino-3-phenyl-6-(pyrrolidin-1-yl)-2-substituted-3,4-dihydroselenopheno [3,2-d]pyrimidines have been accomplished through a base-promoted cas- cade addition/cyclization sequence employing phenyl isothiocyanate fol- lowed by the S-alkylation of the obtained fused Se-containing heterocyclic framework with various alkyl halides. Free radical scavenging activity of the synthesized selenium-containing structures was studied against DPPH, as well. Antioxidant activities as IC50 values were ranged from 12.19 to 91.08mM. Unfused 3-amino-2,4-dicyano-5-(pyrrolidin-1-yl)selenophene was much more powerful antioxidant agent than ascorbic acid. Moreover, the promising antioxidant potentials were observed with selenopheno[3,2- d]pyrimidines. Taking into account the best antioxidant activity of S-benzy- lated derivative amongst pyrimidine-fused heterocycles and significant rela- tionship between antioxidant activity of compounds and many of their biological potencies, using benzyl halides bearing electron donating groups on phenyl ring can probably improve their antioxidant capacities to make them more effective anti-cancer, anti-diabetic, anti-inflammatory and anti-neurodegenerative agents.

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