Synthesis of new heterocycles festooned with thiophene and evaluating their antioxidant activity

The chemical performance of 5-bromo-2-(bromoacetyl)-thiophene (1) was tested toward the reaction with numerous bi-nucleophilic reagents (namely; 2-aminobenzothiazoles, 2-aminothiazole, 2-aminotetrazole, 2-aminotriazole, 2-aminopyridines, 2-aminobenzimidazole and o-phenylenediamine). Therefore, a series of bridged nitrogen heterocycles bearing thiophene moiety 3, 5, 7, 9, 11, 13 and 15, respectively was synthesized. In addition, the reaction of 5-bromo-2-(bromoacetyl)-thiophene with the thiocarbamoyl compounds 17, 19 and/or 24 afforded the corresponding thienyl-thiazoles 18 or dithien-2-yl ketones 20 and 25, based on the reaction conditions. Treatment of 1 with 2-mercapto-4,6-dimethylnicotinonitrile was achieved to obtain the target dithien-2-yl ketone 28. The new synthesized scaffolds were examined for their antioxidant activity by means of ABTS antioxidant assay. The thienyl-thiazole scaffold 18c and 2-((2-[thiophen-2-yl]-2-oxoethyl)thio)nicotinonitrile derivative 27 displayed a reasonable radical scavenging activity.