In continuation of our program aimed at the discovery and development of natural-product-based insecticidal
agents, we have synthesized eighteen alkyl/alkenylacyloxy derivatives at the C-28 position adopting exo-configuration of
toosendanin (3a-r) by the reaction of toosendanin with fatty acids in the presence of N,N’-diisopropylcarbodiimide and 4-
dimethylaminopyridine. Their activity was preliminarily evaluated against the pre-third-instar larvae of Mythimna
separata Walker in vivo. Especially compounds 3e and 3o displayed the more promising insecticidal activity than their
natural precursor, toosendanin. It suggested that for the n-alkyloyloxy series derivatives, the proper length of the side
chain R at the C-28 position of toosendanin was very important for their insecticidal activity.