Novel Meta-Diamide Derivatives Bearing Triazole: Design, Synthesis, and Bioactivity

In searching for novel insecticide lead, 20 new meta-diamide compounds containing triazole were designed and synthesized regarding cyproflanilide as lead compound. All the compounds were characterized by ¹H NMR, ¹³C NMR, and High-resolution mass spectra (HR MS). In preliminary bioassay, we found that one of the compounds: N-(cyclopropylmethyl)-N-(5-((2,6-dibromo-4-(1,2,2,2-tetrafluoro-1-(trifluoromethyl)ethyl)phenyl)carbamoyl)-2-(1H-1,2,4-triazol-1-yl)phenyl)-6-(trifluoromethyl) nicotinamide (16a) had high activity against the target organism Plutella xylostella at 1 mg/L and against the target organism Mythimna separata at 2 mg/L. It is obviously superior to the known compounds I_a and I_b, and it is equivalent to cyproflanilide, and the LC₅₀ values of the compound against P. xylostella and M. separata were 0.90 mg/L and 0.64 mg/L, respectively. It is providing important clues for subsequent structure-activity relationship (SAR) studies. From this, we explored the SAR of these compounds. Through comprehensive analysis of their structural characteristics and insecticidal activity data, we found that different halogen substituents on benzene ring and different aromatic substituents on amino group in the compound had significant effects on insecticidal activity. This has certain guiding significance for further structural optimization and activity enhancement.