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Synthesis of Novel Oxime Sulfonate Derivatives of 2â²(2â²,6â²)-(Di)chloropicropodophyllotoxins as Insecticidal Agents
- Wang, Rong, Zhi, Xiaoyan, Li, Jie, Xu, Hui
- Journal of agricultural and food chemistry 2015 v.63 no.30 pp. 6668-6674
- Mythimna separata, X-ray diffraction, bromine, chlorine, fluorine, insecticidal properties, larvae, mass spectrometry, melting point, mortality, nuclear magnetic resonance spectroscopy, pesticides, pests, podophyllotoxin
- To discover novel natural-product-based pesticidal agents, we prepared a series of oxime sulfonate derivatives of 2â²(2â²,6â²)-(Di)chloropicropodophyllotoxins by structural modification of podophyllotoxin. Their structures were well-characterized by proton nuclear magnetic resonance (1H NMR), high-resolution mass spectrometry (HRMS), optical rotation, and melting point. Moreover, the key steric structure of compound 5f was unambiguously determined by single-crystal X-ray diffraction. Additionally, their insecticidal activity was evaluated at 1 mg/mL against the pre-third-instar larvae of oriental armyworm (Mythimna separata Walker), a typical lepidopteran pest. Among all derivatives, compounds 4c, 5c, and 5d exhibited more promising insecticidal activity, with the final mortality rates greater than 60%, when compared to their precursor podophyllotoxin and the positive control, toosendanin. It demonstrated that introduction of the chlorine atom at the C-2â² or C-2â²,6â² position on the E ring of picropodophyllotoxin or oxime sulfonate derivatives of picropodophyllotoxin was important for the insecticidal activity and introduction of a halogen (e.g., fluorine, chlorine, or bromine) atom-substituted phenylsulfonyl group on the oxime fragment of 2â²(2â²,6â²)-(di)chloropicropodophyllones could lead to more promising compounds.