Synthesis of new heterocycles festooned with thiophene and evaluating their antioxidant activity
Nader A. Abed, Mohamed M. Hammouda, Mohamed A. Ismail, Ehab Abdel‐Latif
Abstract
Abstract 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.