| Plutella xylostella is a major agricultural pest worldwide,causing huge losses worldwideevery year.Due to the long-term use of insecticides for the prevention and control of diamondback moth,diamondback moth has developed severe resistance to traditional insecticides,and there is an urgent need to develop new,green,and efficient insecticides.Based on this,this article has conducted research in the following two directions:1.Isooxazoline insecticide fluralaner is an emergingγ-Aminobutyric acid（GABA）gated chloride ion allosteric modifier broad-spectrum insecticides were synthesized based on the principle of molecular active substructure splicing,replacing the basic piperidine ring of piperine to introduce a linear double amide structure with a fluralaner tail chain.28piperine linear double amide compounds were synthesized,all of which were reported for the first time.The structures of the target compounds were characterized by 1H nuclear magnetic resonance（NMR）,13C NMR,19F NMR,and high-resolution mass spectrometry.The insecticidal activity of this series of compounds against Plutella xylostella was determined by leaf soaking method.The research results found that most compounds exhibited certain insecticidal activity against diamondback moth at 0.20 mg/m L,superior to the lead skeleton piperine and lower than the positive control fluralaner.Compound D28 has the highest insecticidal activity against diamondback moth,with an LC50of 0.38 mg/m L.Through studying the structure-activity relationship,it was found that different substituents R on piperine have a significant impact on the insecticidal activity of the target compound.When R is trifluoroethyl,compound D28 exhibits the best insecticidal activity.When R is an aromatic ring substituent,the activity is highest when the meta substituent on the benzene ring is chlorine.When R is an aliphatic substituent,the activity of aromatic ethyl is highest.2.According to bioelectronic alignment and molecular skeleton transition,19 novel difluoro olefin oxime ether derivatives were synthesized by ring opening and trifluoromethyl activation strategies for trifluoromethylisoxazoline,the core skeleton of fluralaner.The target compounds were characterized by 1H NMR,13C NMR,19F NMR and high-resolution mass spectrometry.Taking compound J16 as an example,the spatial structure of the compound was further determined through X-ray single crystal diffraction.The insecticidal activity of these compounds against diamondback moth and Tetranychus cinnabarinus were measured using leaf soaking method and slide soaking method,respectively.The research results found that most target compounds have moderate to good insecticidal activity against diamondback moth at 0.20 mg/m L.Among them,compounds J1,J5,J6,J9,and J16 have the best activity,with LC50values of 0.12,0.13,0.04,0.19,and 0.11 mg/m L,respectively,but all are lower than the positive control tebufenozide.For the Tetranychus cinnabarinus,compounds J1,J6,J7,J13,J15,and J16 have the best activity.At 0.20 mg/m L,the mortality rates after 72 hours were 80.88%,78.13%,73.14%,85.75%,76.92%,and 100%,respectively,which were higher than the positive control spirodiclofen 62.06%.Moreover,compound J16 has a high mite killing activity against Tetranychus cinnabarinus at 0.10 mg/m L,reaching 82.50%.By studying the structure-activity relationship,it was found that when Y is methyl and X is the benzene ring,and the substituents on the benzene ring are fluorine or meta methyl,the insecticidal and acaricidal activity of the compound can be significantly improved.In addition,when the meta position is trifluoromethyl,the insecticidal activity of the compound can be significantly improved.When Y is methyl and X is pepper ring,it has good activity to kill insects and mites,so J16 is a lead compound with potential research value.In summary,this article conducted a series of studies on natural products such as piperine derivatives and difluoroalkene oxime ethers,and found that D28,J6,and J16have certain insecticidal and acaricidal activities,which can provide a reference for future research. |
