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

Abstract

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 3phenyl 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.

Synthesis, anti-aging and mechanism of magnolol derivatives

“…Based on the existing studies, 12 derivatives of magnolol were designed and synthesized ( Scheme 1 ). Compounds M21-M26 and M29-M31 were synthesized by Williamson alkylation ( Zhang et al, 2022 ). Compound M27 ( Lin et al, 2019 ) was prepared by nitration method ( Li et al, 2021b ).…”

“…Compound M21 was obtained using previously reported methods ( Zhang et al, 2022 ). Yield: 40%, colorless oil, 1 H NMR (Chloroform-d, 400 MHz) δ 7.14 (2H, dd, J = 8.4, 2.3 Hz, H-4, H-4′), 7.06 (2H, d, J = 2.3 Hz, H-6, H-6′), 6.91 (2H, d, J = 8.4 Hz, H-3, H-3′), 5.99 (2H, ddt, J = 16.8, 10.0, 6.7 Hz, H-8, H-8′), 5.19–4.91 (4H, m, H-9, H-9′), 3.76 (6H, s, H-10, H-10′), 3.37 (4H, d, J = 6.8 Hz, H-7, H-7’) 13 C NMR (DMSO-d6, 101 MHz) δ 155.65, 138.54, 131.60, 131.41, 128.69, 128.01, 115.94, 111.78, 55.94, and 39.09…”

“…Additionally, it was found that the cytotoxicity to normal cells could be significantly reduced by methylation/di-methylation at hydroxyl on the phenyl of magnolol ( Rempel et al, 2013 ; Wang et al, 2017 ). In our study, methyl ( Zhang et al, 2022 ) and isopropyl ( Niu et al, 2022 ) groups adding at the hydroxyl group on the phenyl aim to reduce toxicity and increase efficacy. In this experiment, allyl, 2-propynyl ( Niu et al, 2022 ), and nitroso ( Lin et al, 2019 ) with better antioxidant activity were introduced to improve the effect on anti-aging.…”

Research progress of oxazole derivatives in the discovery of agricultural chemicals

“…The LC 50 values of compound 83 against larvae and eggs of T. cinnabarinus were 0.0015 mg/L and 0.008 mg/L, respectively. Also, compound 84 showed 100%, 46.7%, and 56.7% insecticidal activities against M. separata, H. armigera, and P. nubilalis at a concentration of 100 mg/L, respectively [97]. This backbone with 2,6-difluorophenyl substitution at 2-position of 4,5-dihydrooxazole had better insecticidal and acaricidal activity, thus showing the advantages of 2-(2,6-difluorophenyl)-4-phenyl-oxazoline scaffold structure in insecticidal and acaricidal discovery.…”

Preparation and Characterization of Insecticide/Calix[4]arene Complexes and Their Enhanced Insecticidal Activities againstPlutella xylostella

“…Therefore, the development of highly efficient pest-control methods that can reduce pesticide usage is of great importance. Many strategies have been applied to achieve the purpose, such as the discovery of new bioactive compounds − and the optimization of formulations by developing new synergetic adjuvants. , Especially, the development of functional materials as synergists that help to improve the bioactivity, stability, utilization rate, and duration of pesticides has attracted increasing attention due to the feasibility and low R&D cost. − Various types of materials have been reported to have synergistic effects for pesticides, which include metal nanoparticles, graphene oxide, mesoporous silica nanoparticles, polymers, etc . The improved efficacy was majorly achieved by the controlled releasement, increased stability, and higher permeability, which consequently reduced the pesticide residue in the environment. ,, …”