Design, synthesis and insecticidal activities of novel pyrazole amides containing hydrazone substructures

Pyrazole and hydrazone derivatives possess good insecticidal activities; their substructural units are widely used in pesticide design. In an effort to discover new molecules with good insecticidal activities, a series of pyrazole amide derivatives containing hydrazone substructures were synthesised and bioassayed.

Bioassays demonstrated that some of the title compounds exhibited notable control of Plutella xylostella (Linnaeus), Helicoverpa armigera (Hübner), Culex pipiens pallens, Laphygma exigua (Hübner), Spodoptera litura (Fabricius), Nilaparvata lugens (Stål) and Rhopalosiphum maidis (Fitch) at 5, 10, 0.25, 200, 20, 100 and 500 mg L(-1) respectively. Comparative molecular field analysis (CoMFA) based on the bioactivities for P. xylostella was studied; the values of q(2) and r(2) for the CoMFA model were 0.701 and 0.964 respectively.

Some of the title compounds displayed good and broad-spectrum insecticidal activities against different insect species; the CoMFA model revealed that a bulky and negatively charged group at the 4-position of benzene could enhance insecticidal activity. These results could provide useful information for the design of novel insecticide containing substructural units of pyrazole amide and hydrazone.