Design, synthesis and insecticidal-activity evaluation ofN-pyridylpyrazolo-5-methyl amines and its derivatives

In searching for novel insecticidal leads, a series ofN-pyridylpyrazolo-5-methyl amines and their derivatives were designed and synthesized. Among the 22 target compounds obtained, bioassays indicated that some of the target compounds exhibited good insecticidal activities againstPlutella xylostella(P. xylostella) andSpodoptera frugiperda(S. frugiperda). In particular, compound9jrevealed the best insecticidal activity againstP. xylostella, with a LC(50)value of 22.11 mg/L, and compound9qhad the best insecticidal activity againstS. frugiperdawhich with 73.99% of mortality rate at 100 mg/L. Structure-activity relationship (SAR) analysis showed that 4-CF(3)at the position of R(1)linked withN-pyridylpyrazole via amide bond could enhance the insecticidal activity of the target compounds. This study provides valuable clues for the further design and optimization ofN-pyridylpyrazole derivatives.