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BACKGROUND: Pheromone antagonists are good disruptants of the pheromone communication in insects and, as such, have been used in mating disruption experiments. In this study, new non-fluorinated electrophilic keto derivatives structurally related to the pheromone of Cydiapomonella (codlemone) have been synthesised and tested as putative pheromone antagonists. RESULTS: Codlemone (1) was prepared in excellent stereoselectivity in a new, iterative approach involving two Horner – Wadsworth – Emmons reactions. Methyl ketone (2), keto ester (3) and diketone (4) were obtained from codlemone in straightforward approaches in good overall yields and excellent stereochemical purity (≥98% E,E). In electrophysiology, only compound 2 displayed inhibition of the antennal response to the pheromone after presaturation of the antennal receptors. Compounds 2 to 4 did not inhibit the pheromone-degrading enzyme responsible for codlemone metabolism, but mixtures of ketone 2 and diketone 4 with codlemone elicited erratic flights on males in a wind tunnel. In the field, blends of either compound (2 or 4) with the pheromone caught significantly fewer males than codlemone alone. CONCLUSION: Codlemone and the potential antagonists 2 to 4 have been synthesised in good yields and excellent stereoselectivity. These chemicals behave as pheromone antagonists of the codling moth both in the laboratory and in the field. c � 2013 Society of Chemical Industry Supportinginformationmaybefoundintheonlineversionofthisarticle. |
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