Structure-based bioisosterism design, synthesis, insecticidal activity and structure–activity relationship (SAR) of anthranilic diamide analogues containing 1,2,4-oxadiazole rings

BACKGROUND Anthranilic diamide derivatives are among the most important classes of synthetic insecticides. Moreover, the 1,2,4-oxadiazole heterocycle, a bioisostere of amide, has been extensively used in pesticides. In order to discover novel molecules with high insecticidal activities, a series of anthranilic diamide analogues containing 1,2,4-oxadiazole rings were designed and synthesised. RESULTS A series of novel anthranilic diamide derivatives containing 1,2,4-oxadiazole were obtained, and confirmed by 1 H and 13 C nuclear magnetic resonance and high-resolution mass spectrometry. The structure of 3-bromo- N -(4-chloro-2-methyl-6-{3-[(methylsulphonyl)methyl]-1,2,4-oxadiazol-5-yl}phenyl)-1-(3-chloropyridin-2-yl)-1 H -pyrazole-5-carboxamide was further characterised by X-ray diffraction analysis. In addition, bioassays showed that most of the newly synthesised compounds displayed 100% mortality against Plutella xylostella at 100 mg L −1 , and compound 3IIl showed 90% larvicidal activities at a concentration of 0.5 mg L −1 . The LC 50 value of 3IIl was 0.20 mg L −1 , which indicated that it may be used as a potential leading compound for further structural optimisation. Furthermore, brief comparative molecular field analysis (CoMFA) models were established to study the structure–activity relationships (SARs) of the title compounds. CONCLUSION Compound 3IIl may be used as a potential leading compound for further structural optimisation, and SARs and CoMFA models could provide reliable clues for further structural optimisation. © 2016 Society of Chemical Industry