Synthesis of 4β-acyloxypodophyllotoxin analogs modified in the C and E rings as insecticidal agents against Mythimna separata Walker

To discover the new natural-product-based insecticidal agents, four series of sixty novel 4 beta-acyloxypodophyllotoxin analogs modified in the C and E rings were prepared, and their insecticidal activity was tested against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at the concentration of 1 mg/mL. It demonstrated that the position of the dioxo group on the E-ring of 4'-demethylepipodophyllotoxin was regioselectively controlled by the chlorine atom at its C-2' position when 2'-chloro-4'-demethylepipodophyllotoxin was oxidized by sodium periodate. Among all the derivatives, IIIi exhibited the best potent insecticidal activity with the final mortality rate of 63.3%. To alkylacyloxy series, the proper length of the side chain at the C-4 position of Ia-g, IIa-g and IIIa-g was important for their insecticidal activity. (C) 2013 Elsevier Ltd. All rights reserved.