Synthesis, acaricidal activity, and structure–activity relationships of novel phenyl trifluoroethyl thioether derivatives containing substituted benzyl groups

Abstract

BackgroundTo discover and develop novel acaricidal compounds, a series of 2‐fluoro‐4‐methyl/chlorine‐5‐((2,2,2‐trifluoroethyl)thio)aniline/phenol compounds containing N/O‐benzyl moieties were synthesized based on lead compound LZ‐1.ResultsTheir activity against the carmine spider mites (Tetranychus cinnabarinus) were determined by the leaf‐spray method. Bioassays indicated that most of these designed target compounds possessed moderate to excellent acaricidal activity against adults of T. cinnabarinus. The LC50 values of 25b and 26b were 0.683 and 2.448 mg L−1 against the adults of mites, respectively that exceeded those of bifenazate (7.519 mg L−1) and lead compound LZ‐1(3.658 mg L−1). Compound 25b exhibited 100% mortality of larvae of T. cinnabarinus at 10 mg L−1.ConclusionContinuing the study of these compounds further in field trials, we compared the efficacy of mite killing by compound 25b to the commercial pesticide spirodiclofen and showed that mite control achieved 95.9% and 83.0% killing at 10 and 22 days post‐treatment. In comparison, spirodiclofen produced 92.7% killing at 10 days and 77.2% killing at 22 days post‐treatment at a concentration of 100 mg L−1. Results showed that 25b produced more facile and long‐lasting control against T. cinnabarinus than commercialized acaricide spirodiclofen. DFT analysis and electrostatic potential calculations of various molecular substitutions suggested some useful models to achieve other highly active miticidal compounds.This article is protected by copyright. All rights reserved.