Synthesis, insecticidal activities and structure-activity relationship studies of novel anthranilic diamides containing pyridylpyrazole-4-carboxamide

BACKGROUND: Anthranilic diamide insecticides containing pyridylpyrazole-5-carboxamide are extremely important in modern agriculture. New structurally modified compounds with high insecticidal activity were discovered by designing a series of novel pyridylpyrazole-4-carboxamides (9I to 9IV) and pyridylpyrazole-4-carboxamides (10I to 10IV), the latter designed by the cyclisation of two amides. The structure-activity relationship (SAR) between the two series is of interest. RESULTS: Two series of novel anthranilic diamides containing pyridylpyrazole-4-carboxamide were synthesised and characterised via melting point, ¹H NMR, ¹³C NMR, MS and elemental analyses. The insecticidal activities of these compounds against Plutella xylostella were evaluated. At a concentration of 100mgL^-1, the compounds with unmodified amide moieties (9I to 9IV) exhibited much better larvicidal activities than the other derivative compounds (10I to 10IV). Most of the compounds 9I to 9IV showed over 90% larvicidal activity at 100mgL^-1. Furthermore, compounds 9IIIa, 9IIIc, 9IIId and 9IVd displayed significant insecticidal activity at 10mgL^-1. Density functional theory (DFT) calculation was carried out to provide more information regarding SAR. CONCLUSION: Thirty-two new anthranlic diamides containing pyridylpyrazole-4-carboxamide were designed and obtained. SAR analysis and DFT calculation results revealed that the amide moiety had a very important effect on bioactivity. This work has provided information that could aid investigations of novel insecticides.