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Abstract

In order to test a previous conclusion that chain-elongated analogs of (Z)-5-decenyl acetate (1), a pheromone component of the turnip moth, Agrotis segetum, adopt a loop conformation of the terminal alkyl chain in the bioactive conformation, a series of alkyl ether and enol ether analogs of 1 and (Z)-5-dodecenyl acetate (2) have been synthesized and tested using single-cell electrophysiology. In these analogs a methylene group in positions 7 and 9 of 1 and in positions 7 and 11 in 2 have been replaced by an oxygen atom in order to energetically facilitate the formation of a loop conformation in the chain-elongated analogs. The electrophysiological results in combination with molecular mechanics (MM2 and MM3) calculated conformational energies show that the activity decreases of the chain-elongated ether analogs are significantly smaller than that for 2 and that these activity decreases parallel the conformational energies for a loop formation of the terminal chains in the analogs. The results support our previous conclusion that the terminal chain of chain-elongated analogs of 1 adopts a loop conformation in their bioactive conformations.