Design, synthesis and insecticidal activities of novel meta-diamide compounds containing ethyl group

To develop structurally novel and efficient insecticides, a series of ethylpyridine-containing meta-diamide derivatives were designed and synthesized using cyproflanilide as the lead compound. The core bioactive scaffold was retained while integrating active substructure combination and pharmacophore fusion strategies. All compounds were characterized by ¹H NMR, ¹³C NMR, ¹⁹F NMR and HRMS. Preliminary bioassay data showed that some target compounds exhibited good insecticidal activity against Plutella xylostella, Mythimna separata, and Tetranychus cinnabarinus. Particularly, compound 7 g exhibited 100% lethality at a concentration of 1 mg/L against both Plutella xylostella and Mythimna separata; meanwhile, compound 7q achieved complete lethality against Tetranychus cinnabarinus at a concentration of 100 mg/L. Further structure-activity relationship (SAR) analysis based on in vitro efficacy data provided a theoretical foundation for developing next-generation acaricides/insecticides. These findings offer valuable insights for designing novel meta-diamide agrochemicals with enhanced efficacy.