Intermediate derivatisation method in the discovery of new acaricide candidates: synthesis of N‐substituted piperazine derivatives and their activity against phytophagous mites

BACKGROUND To discover and exploit novel acaricidal compounds, a series of novel N‐substituted piperazine derivatives were designed and synthesised using a tert‐butyl piperazine‐1‐carboxylate as the starting material by intermediate derivatisation methods, and their acaricidal activities were evaluated. RESULTS Compounds 11 and 12 exhibited significant acaricidal activity against adults of Tetranychus cinnabarinus in greenhouse tests. Compound 12, in particular, was found to be the best potential candidate acaricide and proved to be more active than the commercial positive controls spirodiclofen and pyridaben, with an LC50 of 0.8977 mg L−1. Results concerning acaricidal activity against larvae and eggs of T. cinnabarinus indicated that compound 12 possessed equivalent larvicidal activity to spirodiclofen and higher larvicidal activity than pyridaben. Meanwhile, compound 12 showed less ovicidal activity than pyridaben, but higher activity than spirodiclofen. Furthermore, the results of the field trial demonstrated that compound 12 could effectively control Panonychus citri and P. ulmi with long‐lasting persistence and rapid action. CONCLUSIONS The present work indicates that compound 12 could be a novel acaricide candidate for spider mite control. © 2016 Society of Chemical Industry