Yuma Sugawara, Hiromitsu Inoue, Satoshi Toda, Jun Tabata
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引用次数: 0
Abstract
The sex pheromone of the azalea mealybug, Crisicoccus azaleae (Tinsley, 1898) (Hemiptera: Pseudococcidae), includes esters of a methyl-branched medium-chain fatty acid, ethyl and isopropyl (E)-7-methyl-4-nonenoate. These compounds are exceptional among mealybug pheromones, which are commonly monoterpenes. Determination of the absolute configuration is challenging, because both chromatographic and spectrometric separations of stereoisomers of fatty acids with a methyl group distant from the carboxyl group are difficult. To solve this problem, we synthesized the enantiomers via the Johnson–Claisen rearrangement to build (E)-4-alkenoic acid by using (R)- and (S)-3-methylpentanal as chiral blocks, which were readily available from the amino acids L-(+)-alloisoleucine and L-(+)-isoleucine, respectively. Each pure enantiomer, as well as the natural pheromone, was subsequently derivatized with a highly potent chiral labeling reagent used in the Ohrui–Akasaka method. Through NMR spectral comparisons of these derivatives, the absolute configuration of the natural pheromone was determined to be S. Field-trap bioassays showed that male mealybugs were attracted more to (S)-enantiomers and preferred the natural stereochemistry. Moreover, the synthetic pheromones attracted Anagyrus wasps, indicating that the azalea mealybug pheromone has kairomonal activity.
期刊介绍:
Journal of Chemical Ecology is devoted to promoting an ecological understanding of the origin, function, and significance of natural chemicals that mediate interactions within and between organisms. Such relationships, often adaptively important, comprise the oldest of communication systems in terrestrial and aquatic environments. With recent advances in methodology for elucidating structures of the chemical compounds involved, a strong interdisciplinary association has developed between chemists and biologists which should accelerate understanding of these interactions in nature.
Scientific contributions, including review articles, are welcome from either members or nonmembers of the International Society of Chemical Ecology. Manuscripts must be in English and may include original research in biological and/or chemical aspects of chemical ecology. They may include substantive observations of interactions in nature, the elucidation of the chemical compounds involved, the mechanisms of their production and reception, and the translation of such basic information into survey and control protocols. Sufficient biological and chemical detail should be given to substantiate conclusions and to permit results to be evaluated and reproduced.