Synthesizing Novel Imidazole‐Conjugated Cyclic Sulfone Derivatives With Amide Fragments and Evaluating Their Insecticidal Activities

ABSTRACT In an effort to identify novel insecticides, we designed and synthesized a series of sulfone compounds incorporating amide fragments, based on the lead compound oxazosulfyl. All synthesized compounds were characterized by 1 H NMR, 13 C NMR, and HR‐MS spectroscopic techniques. The insecticidal activity of these compounds was evaluated against Plutella xylostella and Mythimna separata at concentrations of 1 mg/L ( P. xylostella : 0%–100%; M. separata : 75%–100%) and 0.1 mg/L ( P. xylostella : 0%–30%; M. separata : 0%–65%). Additionally, Aphis craccivora was tested for insecticidal activity at concentrations of 100 mg/L ( A. craccivora : 0%–100%) and 10 mg/L ( A. craccivora : 0%–100%). Preliminary bioactivity assessments showed that most compounds exhibited potent insecticidal activity against P. xylostella and M. separata at 1 mg/L, and against A. craccivora at 100 mg/L. Especially, the compound 9d , N‐(3‐bromo‐5‐(ethylsulfonyl)‐6‐(3‐methyl‐6‐(trifluoromethyl)‐3H‐imidazo[4,5‐b]pyridin‐2‐yl)pyridin‐2‐yl)‐N‐(cyclopropanecarbonyl)cyclopropanecarboxamide ( 9d ), demonstrated remarkable insecticidal activity at a concentration of 1 mg/L, resulting in 100% mortality in both P. xylostella and M. separata . Its activity against M. separata surpassed that of oxazosulfyl ( M. separata : 0%) and matched cyproflanilide ( M. separata : 100%). Even at a lower concentration of 0.1 mg/L, it achieved 50% mortality in M. separata , indicating excellent insecticidal activity. Against A. craccivora at 100 mg/L, it also showed 100% mortality, comparable to imidacloprid. Based on the insecticidal experiments, preliminary structure–activity relationships were investigated and discussed. The findings suggest that sulfone compounds containing amide structural fragments have the potential to be developed into novel insecticides.