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Synthesis of Novel Oxime Sulfonate Derivatives of 2′(2′,6′)-(Di)chloropicropodophyllotoxins as Insecticidal Agents
journal contribution
posted on 2015-08-05, 00:00 authored by Rong Wang, Xiaoyan Zhi, Jie Li, Hui XuTo
discover novel natural-product-based pesticidal agents, we prepared
a series of oxime sulfonate derivatives of 2′(2′,6′)-(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-2′
or C-2′,6′ 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 2′(2′,6′)-(di)chloropicropodophyllones
could lead to more promising compounds.