Design, Synthesis, Acaricidal Activity, Structure–Activity Relationship, and Molecular Docking of Novel Piperidine Amine Derivatives Containing a Pyrimidine Motif

Tetranychus cinnabarinus, a prominent mite in agricultural crops, has developed escalating resistance as a result of extensive and repeated chemical pesticide application. Consequently, it remains a quite urgent goal to identify novel structures with high efficacy to reduce resistance. In this study, a series of novel piperidine pyrimidinamine derivatives were designed and synthesized by employing the intermediate derivatization method (IDM) and then screened for their acaricidal activity. Bioassays indicated that most of the target compounds exhibited some acaricial activities against T. cinnabarinus; especially, the lead compounds 15 and 23 displayed excellent acaricidal activity with an LC 50 of 1.55 mg/L and 1.46 mg/L, respectively, significantly better than the commercialized acaricide pyridaben. Their structure–activity relationship was discussed, and the field tests were also conducted. It was concluded that lead compounds 15 and 23 with a novel structure and excellent acaricidal potency were worthy of being further optimized for a promising agrochemical acaricide candidate.