Diastereocontrolled Syinthesis of both enantiomers of Trifluoromethyl frontalin

Frontalin is the aggregation pheromone of the Dendroctonus brevicomis pine bark beetles: the predominant enantiomer usually depends on the species and of the sex of insects. In order to evaluate the influence of fluorosubstitution on the biological activity, fluorosubstituted pheromones are being synthesized. The first synthesis of both the enantiomers of frontalin showing a trifluoromethyl moiety on the 1 position of the 6,8-dioxabicyclo[3 .2.1]octane framework was realized. The methylene insertion on the ketone moiety by diazomethane, followed by oxirane ring opening in acidic medium. the one-pot reaction via Wacker-oxidation and ketalization without loss of diastereomeric purity and the hydrogenolytic removal of the sulfinyl chiral auxiliary were the key steps of the synthetic procedure.