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

Phenylpyrazole insecticides are widely used for cropprotectionand public sanitation by blocking gamma-aminobutyric acid (GABA)-gatedchloride channels and glutamate-gated chloride (GluCl) channels. Herein,36 novel phenylpyrazole derivatives containing a trifluoromethylselenylmoiety were designed and synthesized based on the strategy of introducinga selenium element. All derivative structures were characterized bynuclear magnetic resonance (NMR) and high-resolution mass spectrometry(HRMS). The insecticidal activity results indicated that some derivativeshad 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/Lwas 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 mortalityrates of 87 and 93% at 50 mg/L, respectively. It was summarized thatthe different binding poses of fipronil and compounds 5 and 6 in the Musca domestica (M. domestica) GABARs might leadto the disparity in bioactivity from docking studies. Toxicity testson zebrafish suggested that compound 6 may be slightlyless toxic to the embryos than fipronil on hatching rate.