Synthesis, Insecticidal Activities, and Structure–Activity Relationship of Phenylpyrazole Derivatives Containing a Fluoro-Substituted Benzene Moiety

Abstract

Fluorinated organic compounds represent a growing and important family of commercial chemicals. Introduction of fluorine into active ingredients has become an effective way to develop modern crop protection products. Given the particular properties of fluorine and high efficiency and selectivity of diamide insecticides, we designed and synthesized 27 anthranilic diamides analogues containing fluoro-sustituted phenylpyrazole. A preliminary bioassay indicated that most target compounds exhibited good biological activity against <i>Mythimna separata</i> and <i>Plutella xylostella</i>. Compound <b>IIIf</b> containing a 2,4,6-trifluoro-substituted benzene ring showed 43% insecticidal activity against <i>M. separata</i> at 0.1 mg L^-1, while the control chlorantraniliprole was 36%. The activity of <b>IIIe</b> against <i>P. xylostella</i> at 10^-5 mg L^-1 was 94%, compared with that of the control being 70%. Thus, introduction of fluorine into diamide insecticides was useful for increasing activity. Insect electrophysiology studies showed that the calcium concentration in the nerve cells of third <i>M. separata</i> larvae was elevated by <b>IIIf</b>, which further confirmed that ryanodine receptor (RyR) was its potential target.