Design, Synthesis, and Biological Activities of Novel Phenylpyrazole Derivatives Containing a Trifluoromethylselenyl Moiety.

Phenylpyrazole insecticides are widely used for crop protection and public sanitation by blocking gamma-aminobutyric acid (GABA)-gated chloride channels and glutamate-gated chloride (GluCl) channels. Herein, 36 novel phenylpyrazole derivatives containing a trifluoromethylselenyl moiety were designed and synthesized based on the strategy of introducing a selenium element. All derivative structures were characterized by nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). The insecticidal activity results indicated that some derivatives had good insecticidal activities against Aedes albopictus ( A. albopictus ) and Plutella xylostella ( P. xylostella ). The larvicidal activity against mosquitos of compounds 5 , 5a , 5k , and 5l at 0.5 mg/L was 60-80%. At a concentration of 500 mg/L, compounds 5 , 5a , 5h , 5k , 5l , 5r , 6 , 6j , 6k , and 7 showed a 70-100% mortality against P. xylostella . Among them, derivatives 5 and 6 had a better insecticidal effect with mortality rates of 87 and 93% at 50 mg/L, respectively. It was summarized that the different binding poses of fipronil and compounds 5 and 6 in the Musca domestica ( M. domestica ) GABARs might lead to the disparity in bioactivity from docking studies. Toxicity tests on zebrafish suggested that compound 6 may be slightly less toxic to the embryos than fipronil on hatching rate.