Oriented synthesis and insecticidal activities of novel meta-diamide scaffolds incorporating with 1,2,4-triazole moiety

In an effort to discover a new insecticide, we designed and synthesized a series of novel meta-diamide compounds containing 1,2,4-triazole with cyproflanilide as a lead compound. All the compounds were characterized by ¹H NMR, ¹³C NMR, and HR-MS. Both Plutella xylostella and Mythimna separata were tested for their insecticidal activity at 200 mg/L (P. xylostella: 0%–100%; M. separata: 0%–100%), 20 mg/L (P. xylostella: 0%–97%; M. separata: 0%–100%), and 2 mg/L (P. xylostella: 0%–97%; M. separata: 0%–100%), while Aphis craccivora was tested for its insecticidal activity at 400 mg/L (A. craccivora: 0%–36%). Further studies are needed to investigate the insecticidal activity of A. craccivora. Preliminary bioactivity results showed that most of the compounds had good insecticidal activity at 200 mg/L against P. xylostella and M. separata. Especially, the compound 7p, N-(cyclopropylmethyl)-N-(5-((2,6-dibromo-4-(perfluoropropan-2-yl)phenyl) carbamoyl)-2-(1H-1,2,4-triazol-1-yl)phenyl)-6-(trifluoromethyl)nicotinamide (7p), showed good insecticidal activity at even lower doses of 2 mg/L (P. xylostella: 97%; M. separata: 100%), which was equivalent to that of the lead compound cyproflanilide (P. xylostella: 100%; M. separata: 100%), as well as significantly better than the two known compounds I_a (P. xylostella: 97%; M. separata: 0%) and I_b (P. xylostella: 60%; M. separata: 0%). Preliminary structure–activity relationship was also discussed based on insecticidal tests. The results indicate that meta-diamide compounds containing 1,2,4-triazole can be developed as novel insecticides.