Synthesis And Bioactivity Of Novel Pyrazole Oxime Ether Derivatives

Crop diseases and insect pests are important factors that affect food production.Pesticides are a central part of plant protection and have an irreplaceable role in agricultural production.Overuse of pesticides causes serious environmental pollution and resistance problems.Therefore,finding new pesticides with broad spectrum,high efficiency,low toxicity,and low residue has become the focus of pesticide researchers.Nitrogen-containing heterocyclic compounds are widely used in the field of pesticides due to their flexible structure,high activity and selectivity.Pyrazole oxime is an important nitrogen-containing heterocyclic structure,many common pesticides contain pyrazole ring structure,such as fenpyroximate,pyridoxamine,pyrisidine.In addition,1,2,3-triazole,tetrazolium,oxazole,and 1,3,4-oxadiazole structure are also common pesticides and pharmaceutical intermediates.In order to find highly active pyrazole oxime ethers,four series and a total of sixty-four pyrazolyl oxime ether with 1,2,3-triazole,tetrazolium,oxazole,1,3,4-oxadiazole moiety were desgined and synthesized according to the structures of fenpyroximate by the methods of bioisoterism and union of active groups.The structures of the intermediates and the target compounds were identified by ¹H NMR,¹³C NMR and elemental analysis.Preliminary bioassay data showed that most pyrazole oxime ether compounds containing 1,2,3-triazole,tetrazolium,oxazole,and1,3,4-oxadiazole ring displayed good insecticidal and acaricidal activity.At the concentration of 500μg/mL,compounds A3,A4,A6,A8,A9,A10,A11,A12,A13,B9,B10,B11,B13,C2,C4,C6,C8,C9,C10,C12,C13,C6,D2,D5,D7,D9,D11and D13 all exhibited 100%insecticidal activity against Oriental armyworm and Aphis craccivora,compounds B2,B4,B5,B8,B9,B10,B11,B12 and B13 displayed100%insecticidal activity against Nilaparvata lugens,compounds A3,A4,A6,A10,A11,A12,A13,C2,C6 and D12 exhibited 100%acaricidal activity against Tetranychus cinnabarinus.In addition,at the concentration of 100μg/mL,compounds A2,A9,A11,A12 and A16 showed 100%insecticidal activity against Oriental armyworm,compounds A12 displayed 100%insecticidal activity against Aphis craccivora,compounds A3 and A10 had 90%acaricidal activity against Tetranychus cinnabarinus.At the concentration of 20μg/mL,compound A9indicated 100%insecticidal activity against Oriental armyworm,which were better than that of the control Tolfenpyrad.A total of sixty-four pyrazole oxime derivatives reported in this paper have good insecticidal and acaricidal activity.Moreover,the methods of synthesis and the data of bioassay can provide important theoretical and experimental bases for the further study on the structural design,synthesis and structure activity relationship of pyrazole oxime compounds in the future.Some of the target compounds can also be selected as the lead compounds for further study.