Design, Synthesis, and Pesticidal Activities of Novel Pyrimidin‐4‐amine Derivatives Containing Trifluoroethyl Sulfide Moiety

In order to overcome the problem of pesticide resistance, it is necessary to discover novel pesticides with new mechanisms of action. Herein, a series of novel pyrimidin-4-amine derivatives containing trifluoroethyl sulfide moiety were designed and synthesized. Bioassays indicated that the title compounds synthesized possessed excellent acaricidal activity against Tetranychus urticae and fungicidal activity against Erysiphe graminis and Puccinia sorghi. Especially, the acaricidal activity of 5-chloro-6-(difluoromethyl)-N-(2-(2-fluoro-4-methyl-5-((2,2,2-trifluoroethyl)thio)phenoxy)ethyl)pyrimidin-4-amine (compound T4, LC50 = 0.19 mg/L) against T. urticae was close to commercial acaricide cyenopyrafen, and the fungicidal activity of 5-chloro-6-(difluoromethyl)-2-methyl-N-(2-(3-((2,2,2-trifluoroethyl)thio)phenoxy)ethyl)pyrimidin-4-amine (compound T15, EC50 = 1.32 mg/L) against P. sorghi. was superior to commercial fungicide tebuconazole. The synthesis and characterization of these compounds were given and the structure-activity relationships were discussed. By connecting the key intermediate trifluoroethyl sulfide with pyrimidinamine, we obtained T4 with LC50 was 0.19 mg/L against T. urticae and T15 with EC50 was 1.32 mg/L against P. sorghi after active testing and structural optimization. image