|Siegler, M - Johns Hopkins University|
Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2014
Publication Date: 11/19/2014
Publication URL: http://handle.nal.usda.gov/10113/60199
Citation: Khrimian, A., Shirali, S., Vermillion, K., Siegler, M.A., Guzman, F., Chauhan, K.R., Aldrich, J.R., Weber, D.C. 2014. Determination of the stereochemistry of the aggregation pheromone of harlequin bug, Murgantia histrionica. Journal of Chemical Ecology. 40:1260-1268. Interpretive Summary: Insect pests cause a significant damage to crops and forest, and monitoring their populations aids greatly to reducing the pesticide use and biological control. Pheromones, or chemicals that trigger a natural behavioral response in another member of the same species, are commonly used as baits for sampling inset populations. Detailed structures of pheromones of several key stink bug species had not been determined because selective syntheses of the candidate pheromones with exact spatial arrangements of structural elements (stereoisomers) had not been developed. These included the harlequin bug, which is a serious stink bug pest of cole crops. Here, we completed syntheses of all stereoisomers of a known harlequin bug pheromone “murgantiol” and found that the natural pheromone consists not just one (as previously suggested) but two stereoisomers, produced by the bug in 1.4:1 ratio. Both stereoisomers are important for field attractiveness. The results of this study are of interest to other chemists and entomologist involved in the research of potential pest control compounds, and to state and federal agencies involved in monitoring and controlling insect pests of agriculture and forest.
Technical Abstract: Preparation of a complete stereoisomeric library of 1,10-bisaboladien-3-ols and selected 10,11-epoxy-1-bisabolen-3-ols was earlier pivotal for the identification of the aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys. Herein, we describe syntheses of remaining10,11-epoxy-1-bisabolen-3-ols and provide additional evidence on the assignment of relative and absolute configurations of these compounds by single-crystal X-ray crystallography of an intermediate (3S,6R,7R,10S)-1-bisabolen-3,10,11-triol (12). To demonstrate yet another utility of the stereoisomeric library, we revisited the harlequin bug, Murgantia histrionica, aggregation pheromone, and discovered that the male-produced pheromone consists of two stereoisomers of 10,11-epoxy-1-bisabolen-3-ol. Employment of eight cis-10,11-epoxy-1-bisabolen-3-ol stereoisomeric standards, two enantioselective GC columns and NMR spectroscopy enabled the identification these compounds as (3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol and (3S,6S,7R,10R)-10,11-epoxy-1-bisabolen-3-ol, produced by M. histrionica males in 1.4:1 ratio.