Pheromone synthesis. Part 263: Synthesis of the racemate and the enantiomers of (E)-cis-6,7-epoxy-2-nonenal,the male-produced pheromone of the red-necked longhorn beetle,Aromia bungii

The racemate and the enantiomers of (E)-cis-6,7-epoxy-2-nonenal, the male pheromone of Aromia bungii, were synthesized by olefin cross metathesis between crotonaldehyde and (±)-, (+)- and (?)-cis-3,4-epoxy-7-octene. The epoxide was prepared by the Grignard coupling between allylmagnesium bromide and (±)-, (+)- and (?)-cis-2,3-epoxypentyl triflate. (±)-cis-2,3-Epoxy-1-pentanol was prepared by MCPBA epoxidation of (Z)-2-penten-1-ol, while its enantiomers were synthesized by the Sharpless asymmetric epoxidation of the allylic alcohol.