Synthesis and fungicidal activity of novel 4(3H)-quinazolinone Schiff base derivatives

A series of novel 4(3H)-quinazolinone Schiff base derivatives were synthesized using 2-amino-4-chlorobenzoic acid as the starting material. The structures of the resultant compounds were characterized by IR,1H NMR, MS and elementary analyses. The preliminary bioassay data showed that the final compounds exhibited fungicidal activities with different levels. Phomopsis mangiferae Ahmad were sensitive to most of the compounds. In particular, 7e showed potential antifungal activity against Corynespora cassiicola Wei and Phomopsis mangiferae Ahmad with the inhibition rates of 26.21%±1.11% and 98.18%±1.07%, respectively, which were equal to those of the fungicide chlorothalonil (25.64%±1.31% and 100%, respectively) at the concentration of 100 μg/mL. The preliminary Structure Activity Relationships (SAR) revealed that electron-withdrawing groups were favorable for improving antifungal activities of the title compounds.