Design, Synthesis, and Insecticidal Activities of Imidazo[4,5‐b]Pyridine Compounds Containing Amino Fragment

In order to develop new insecticides to solve the problem of pests, a series of imidazo[4,5-b]pyridine compounds containing amino fragments were synthesized and characterized by proton nuclear magnetic resonance (¹H NMR), carbon-13 NMR (¹³C NMR), and high-resolution mass spectrometry. The preliminary bioassay result indicated that most of the synthesized compounds exhibited excellent insecticidal activities against Nilaparvate lugens and Mythimna separata. Especially, 5-(ethylsulfonyl)-6-(3-methyl-6-(trifluoromethyl)-3H-imidazo[4,5-b]pyridin-2-yl)-N-(4-methylbenzyl)pyridin-2-amine (8n) exhibited 46.85 % mortality against N. lugens at 5 mg/L, better than Oxazosulfyl (0.00 % at 5 mg/L). Meanwhile, 5-(ethylsulfonyl)-6-(3-methyl-6-(trifluoromethyl)-3H-imidazo[4,5-b]pyridin-2-yl)-3-phenylpyridin-2-amine (10a) exhibited 100.00 % mortality against M. separata and Plutella xylostella at 1 mg/L, better than Oxazosulfyl against M. separata (0.00 % at 1 mg/L) and P. xylostella (96.67 % at 1 mg/L). Further, the preliminary structure-activity relationship was discussed. The work demonstrated that the prepared compounds containing amino fragments imidazo[4,5-b]pyridin can supply certain hints by structure optimization for the development of new insecticides.