Synthesis and Bioactivities of Novel Pyrazole Oxime Ester Derivatives Containing Pyridyl Moiety

Abstract

In order to explore novel pyrazole derivatives with good biological activities, a series of novel pyrazole oxime ester compounds containing pyridyl moiety were designed and synthesized according to the method of active substructure combination. The structures of the target compounds were determined by 1H NMR, 13C NMR and elemental analysis. Preliminary bioassay data indicated that some of the title compounds showed certain insecticidal activities. At a concentration of 500 μg/mL, seven compounds exhibited insecticidal activity againstOriental armyworm with 50%~90%, and six compounds exhibited insecticidal activity against Aphis medicaginis with 50%~90%. When the dosage was lowered to 100 μg/mL, 1,3-dimethyl-5-(4-chlorophenoxy)pyrazole-4-formyl-O-(2-chloropyridin-3-formyl)oxime (5f) and 1,3-dimethyl-5-(4-methylphenoxy)pyra-zole-4-formyl-O-(2-chloropyridin-3-formyl)oxime (5j) were still active against Aphis medicaginis with inhibitory values of 50% and 50%, respectively. Insecticidal activities against Nilaparvata lugens of 1,3-dimethyl-5-(3-fluorophenoxy)pyrazole-4-formyl-O-(2-chloropyridin-3-formyl)oxime (5b) and 5f were both 100% at 500 μg/mL. Additionally, 1,3-dimethyl-5-(4-fluorophenoxy)pyrazole-4-formyl-O-(2-chloropyridin-3-formyl)oxime (5c), 1,3-dimethyl-5-(3-chlorophenoxy)-pyrazole-4-for-myl-O-(2-chloropyridin-3-formyl)oxime (5e), 1,3-dimethyl-5-(4-trifluoromethoxyphenoxy)pyrazole-4-formyl-O-(2-chloro-pyridin-3-formyl)oxime (5i) and 5j displayed good anti-tumor activity against HepG2 cells with IC50 values of 2.6, 4.6, 1.8and1.1 μmol/L, respectively.