ARS | Publication request: Pheromone synthesis. Part 245: Synthesis and chromatographic analysis of the four stereoisomers of 4,8-dimethyldecanal, the male aggregation pheromone of the red flour beetle, Tribolium castaneum

Submitted to: Tetrahedron
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 27, 2010
Publication Date: January 7, 2011
Repository URL: http://ddr.nal.usda.gov/handle/10113/49944
Citation: Akasaka, K., Tamogami, S., Beeman, R.W., Mori, K. 2011. Pheromone synthesis. Part 245: Synthesis and chromatographic analysis of the four stereoisomers of 4,8-dimethyldecanal, the male aggregation pheromone of the red flour beetle, Tribolium castaneum. Tetrahedron. 67(1):201-209. doi: http://dx.doi.org/10.1016/j.tet.2010.10.086.

Interpretive Summary: Insect pheromones are critically important components in lure-based traps for pest monitoring or control. The red flour beetle aggregation pheromone, “Tribolure”, has been used commercially for several decades for trapping and monitoring of this pest in flour mills and warehouses, but no one has ever identified the natural blend of Tribolure isomers produced by insects. An unnatural blend of isomers could unnecessarily reduce trap efficacy. We synthesized all four stereoisomers of Tribolure and determined that the natural pheromone contains all four. However, the commercial blend contains only three of the four, potentially limiting its potency. This research could lead to more effective attractants for monitoring or control of flour beetles.

Technical Abstract: All four stereoisomers of 4,8-dimethyldecanal (1) were synthesized from the enantiomers of 2-methyl-1-butanol and citronellal. Enantioselective GC analysis enabled separation of (4R,8R)-1 and (4R,8S)-1 from a mixture of (4S,8R)-1 and (4S,8S)-1, when octakis- (2,3-di-O-methoxymethyl-6-O-t-butyldimethylsilyl)-'-cyclodextrin was employed as a chiral stationary phase. Complete separation of the four stereoisomers of 1 on reversed phase HPLC at –54 degrees C was achieved after oxidation of 1 to the corresponding carboxylic acid 14 followed by its derivatization with (1R,2R)- or (1S,2S)-2-(2,3-anthracenedicarboximido)cyclohexanol, and the natural pheromone was found to consist of a mixture of all four stereoisomers.