title: Chirality of synergistic sex pheromone components of the western hemlock looperLambdina fiscellaria lugubrosa (HULST) (Lepidoptera: Geometridae).
abstract: Bakers' yeast reduction of (2E)-3-(2'-furanyl)-2-methyl-2-propenal yielded the synthetic intermediate, (2S)-3-(2'-furanyl)-2-methylpropanol, of high chiral purity (>97% ee) for the synthesis of the enantiomers of 2,5-dimethylheptadecane and 7-methylheptadecane, two synergistic sex pheromone components of the western hemlock looper (WHL),Lambdina fiscellaria lugubrosa Hulst. In electrophysiological bioassays, (7S)- but not (7R)-7-methylheptadecane elicited strong antennal responses by male WHL antennae. In field trapping experiments, addition of (7S)- but not (7R)-7-methylheptadecane to (5R,11S)-5,11-dimethylheptadecane, the major sex pheromone component of WHL, increased attraction. Attraction to (5R,11S)-5,11-dimethylheptadecane in combination with (7S)-7-methyiheptadecane was further enhanced by the addition of (5S)- but not (5R)-2,5-dimethylheptadecane. Similarly, attraction to (5R,11S)-5,11-dimethylheptadecane combined with (5S)-2,5-dimethylheptadecane increased when 7S- but not (7R)-7-methylheptadecane was added as a third component. We conclude that (7S)-7-methylheptadecane and (5S)-2,5-dimethylheptadecane are the synergistic sex pheromone components of WHL. The synthetic methodology described is applicable to the synthesis of chiral methyl-branched pheromones in other orders of the Insecta, particularly Coleoptera, Diptera and Orthoptera.
authors.affiliation: Departments of Chemistry, Simon Fraser University, V5A 1S6, Burnaby, British Columbia, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: G
authors.initials: G
authors.lastname: Gries
authors.forename: R
authors.initials: R
authors.lastname: Gries
authors.forename: J
authors.initials: J
authors.lastname: Bikic
authors.forename: K N
authors.initials: KN
authors.lastname: Slessor