Alkyl-Substituted δ-Lactones Derived from Dihydrojasmone and Their Stereoselective Fungi-Mediated Conversion: Production of New Antifeedant Agents

摘要

A chemoenzymatic method was applied to obtain optically pure alkyl-substituted δ-lactones. First, chemical Baeyer–Villiger oxidation of dihydrojasmone ( 1 ) was carried out, affording two new alkyl-substituted δ-lactones: 3,4-dihydro-5-methyl-6-pentyl-2 H -pyran-2-one ( 2 ) and 5-methyl-6-pentyl-1,13-dioxabicyclo[4.1.0]heptan-2-one ( 3 ). In the next step, fungal strains were investigated as biocatalysts to enantioselective conversion of δ-lactones ( 2 ) and ( 3 ). The fungal cultures: Fusarium culmorum AM10, Fusarium equiseti AM15 and Beauveria bassiana AM278 catalyzed the stereoselective hydration of the double bond of lactone ( 2 ) (ee = 20%–99%) while Didymosphaeria igniaria KCh6670 proved to be the best biocatalyst for the reduction of carbonyl group in the epoxylactone ( 3 ) (ee = 99%). In both cases, chiral oxyderivatives were obtained in low to high yields (7%–91%). The synthetic lactones ( 2 ), ( 3 ) and its derivatives ( 4 ), ( 5 ) were tested for their antifeedant activity towards larvae and adults of lesser mealworm ( Alphitobius diaperinus Panzer) and peach potato aphid ( Myzus persicae [Sulzer]) and some of them were active towards studied insects.