Synthesis and Insecticidal Activities of Novel Derivatives of 1β,4α,6α,9α-Tetrahydroxy-2β,12-epoxymethano-β-dihydroagarofuran

Abstract

In order to develop novel biorational pesticides, twelve new ether derivatives of 1β,4α,6α,9α-tetrahydroxy-2β,12-epoxymethano-β-dihydroagarofuran (3) were synthesized. The structure of the important intermediate 3 was confirmed by X-ray crystallography, and the new derivatives (3.1–3.12) were elucidated by IR, ¹H NMR, ¹³C NMR and 2D NMR spectroscopic and ESI-MS analysis. Insecticidal activities of these derivatives were tested against the third-instar larvae of Mythimna separata. Though most of the derivatives (3.1–3.4, 3.6, 3.8, 3.9–3.12) revealed no obvious activities at the concentration of 10 mg/mL ^–1, two compounds 3.5 and 3.7, with KD₅₀ values of 12.9 (μg/g-¹ and 7.8 μg/g ^–1, respectively, showed much higher insecticidal activities than celangulin-V, with a KD₅₀ of 321.4 μg·g^–1, the main insecticidal component from the root bark of Chinese bittersweet, Celastrus angulatus Max. The results showed that β-dihydroagarofuran has the potential to be a lead structure for semi-synthetic green insecticides.