Natural products-based insecticidal agents 9. Design, semisynthesis and insecticidal activity of 28-acyloxy derivatives of toosendanin against Mythimna separata Walker in vivo

In continuation of our program aimed at the discovery and development of natural products-based insecticidal agents, twelve 28-acyloxy derivatives of toosendanin (2a-l) were semisynthesized and preliminarily evaluated their activity against the pre-third-instar larvae of Mythimna separata Walker in vivo at the concentration of 1 mg/mL. Some compounds exhibited the potent insecticidal activity. Especially compounds 2c and 2j displayed the more promising insecticidal activity than their natural precursor, toosendanin, a commercial insecticide derived from Melia azedarach at 1 mg/mL. In general, it indicated that the butanoyloxy or phenylacryloyloxy moiety at the 28-position of toosendanin was essential for the insecticidal activity.