Design, Synthesis, Acaricidal Activities, and Structure-Activity Relationship Studies of Oxazolines Containing Ether Moieties.

To develop highly efficient and low cost acaricides, a series of 2,4-diphenyl-1,3-oxazolines containing an ether moiety at the para position of the 4-phenyl group were synthesized from different alcohols and phenols. The bioassay results showed that most of the compounds, especially the short-chain alkyl ethers, exhibited excellent acaricidal activity against both the larvae and the eggs of Tetranychus cinnabarinus . In particular, the n -propyl ether compound Ic possessed much better larvicidal activity (LC 50 = 0.0015 mg/L) and ovicidal activity (LC 50 = 0.0008 mg/L) than commercial acaricide etoxazole (LC 50 = 0.0145 and 0.02 mg/L for larvae and eggs, respectively). In addition, some compounds also exhibited insecticidal activity, especially compound Iw (4-CF 3 -phenyl ether) showed higher mortality than etoxazole against Mythimna separata , Helicoverpa armigera , and Pyrausta nubilalis . Considering the high acaricidal activity and relatively low cost, Ic was worthy of further study as an acaricide agent. An alternative synthetic route for the large-scale synthesis of Ic was then studied.