Synthesis and Insecticidal Activities of New Ester-Derivatives of Celangulin-V

In order to develop new biorational pesticides, ten new 6-substituted ester derivatives of Celangulin-V were designed and synthesized. The structures of the new derivatives were confirmed by IR, (1)H-NMR, (13)C-NMR and ESI-MS spectral analysis. Insecticidal activities of these compounds were tested against the third-instar larvae of Mythimna separata. Two derivatives (1.1, 1.2) showed higher insecticidal activities than Celangulin-V, with mortality of 75.0% and 83.3%, respectively. While four compounds (1.3, 1.4, 1.7, 1.8) denoted lower insecticidal activities, the others (1.5, 1.6, 1.9, 1.10) revealed no activities at a concentration of 10 mg.mL(−1). The results suggest that C-6 substitutions of Celangulin-V are very important in determining the insecticidal activities of its ester-derivatives. That the acetyl (1.1) and propionyl (1.2) derivatives possessed much higher insecticidal activities than Celangulin-V itself supported the view that Celangulin-V has the potential to be a lead structure of semi-synthetic green insecticides.