Synthesis and bioassay studies of benzoxazin-4-one and quinazolin-4-imine derivatives

Abstract

The 4H-3,1-benzoxazin-4-one and quinazolin-4-imine derivatives have been synthesized in simple and one step reaction. The reaction of anthranilic acid and benzoyl chloride, terephtaloyl dichloride and 4-chlorobenzoyl chloride in pyridine yielded 2-phenyl-4H-3,1-benzoxazin- 4-one (78.91%), 1,4-(di-4H-3,1-benzoxazin-4-one)benzene (55.23%) and 2-(p-chlorophenyl)-4H-3,1,-benzoxazine-4-one (33.20%) respectively. The benzoxazin-4-one derivatives were then treated with hydrazine hydrate in absolute ethanol to form 2-phenylquinazolin-4-imine (70.90%), 1,4-(diquinazolin-4-imine)benzene (43.70%) and 2-(p-chlorophenyl)quinazolin-4-imine (35.81%). The resulting compounds were characterized using ATR and 1H NMR using CDCl3 as solvent. From both spectra it showed that the synthesis of targeted compound, 4H-3,1-quinzolin-4-one was unsuccessful. The resulting compounds after treated with hydrazine hydrate were proposed to be quinazolin-4-imine compounds based on the data analyzed from ATR and 1H NMR spectrum. Antioxidant test using DPPH free radical scavenging has been carried out on the six compounds synthesized. The results showed that 4H-3,1-benzoxazin-4-one derivatives did not show antioxidant activity while the compounds of quinazolin-4-imine derivatives showed good antioxidant activity as the IC50 value obtained are lower than positive control of ascorbic acid except for 1,4-(diquinazolin-4-imine)benzene. Among the quinazolin-4-imine derivatives, 2-phenylquinazolin-4-imine showed the highest antioxidant activity at IC50 value at 2.66ppm. The introducing of electron withdrawing group at phenyl substituent was found to reduce ability of compounds in antioxidant activity.