Design, Synthesis, and Biological Activities of Novel 1,3,5-Trimethylpyrazole-Containing Malonamide Derivatives

New 1,3,5-trimethylpyrazole-containing malonamide derivatives based on pyflubumide were designed, synthesized, and characterized using1H-NMR,13C-NMR, and high-resolution mass spectra (HRMS). The results of preliminary bioassays showed that the target compounds possessed good activities againstTetranychus cinnabarinus,Plutella xylostella, andAphis craccivora. Most of the target compounds exhibited moderate to good acaricidal activity againstTetranychus cinnabarinusat a concentration of 400 µg/mL, and some showed moderate activity at a concentration of 200 µg/mL; in particular, compounds8mand8pexhibited 70.0% mortality. In addition, some of the target compounds exhibited good insecticidal activities againstPlutella xylostellaat a concentration of 200 µg/mL, especially compounds8iand8o,which achieved 100.0% mortality at a concentration of 100 µg/mL. Interestingly, some of the target compounds exhibited potent anti-aphid activity againstAphis craccivoraat a concentration of 200 µg/mL; furthermore, compounds8pand8qdemonstrated 100.0% anti-aphid activity at a concentration of 50 µg/mL. The preliminary analyses of the structure–activity relationships (SAR) indicated that the acaricidal and insecticidal activities varied significantly depending on the type of substituent and substitution pattern, which provides guidance for the further investigation of such structural modifications.Keywords:malonamide;pyflubumide;synthesis;acaricidal and insecticidal activities