Abstract

SYNTHESIS AND IN VITRO ANTIOXIDANT ACTIVITY OF SUBSTITUTED ?-CYANO-N-(5-METHYLISOXAZOL-3-YL) CINNAMIDES

Madhavi Kuchana*

ABSTRACT

A series of substituted α-cyano-N-(5-methylisoxazol-3-yl) cinnamides were prepared by using 2-cyano-N-(5-methylisoxazol-3-yl)acetamide and substituted benzaldehydes as starting materials. The starting compound, 2-cyano-N-(5-methylisoxazol-3-yl)acetamide was synthesized by cyanoacetylation of 3-amino-5-methylisoxazole with mixture of cyanoacetic acid and acetic anhydride in presence of anhydrous pyridine. The title compounds were formed by the knoevenagel condensation of active methylene group of 2-cyano-N-(5- methylisoxazol-3-yl)acetamide with substituted benzaldehydes in toluene containing small amounts of glacial acetic acid and piperidine. Twelve final compounds were prepared using above procedure. All the compounds were purified by recrystallization from suitable solvent and characterized by spectral and analytical methods. The title compounds were evaluated for in vitro antioxidant activity by scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical at 100 μM concentration. Among the series, compounds with phenolic hydroxyl group on α-cyanocinnamide moiety were found to possess good anti-oxidant properties.

Keywords: Isoxazole, ?-cyanocinnamide, knoevenagel condensation, in vitro – antioxidant activity