Synthesis of (7Z,9Z)-dodecadienyl acetate, a component of sex pheromones of the leafrollers Epinotia and Eucosma, using conjugated diynols

Article abstract of DOI:10.1007/BF00699203

Two analogous routes to the title pheromones were elaborated based on organocuprate cross-coupling of Z,Z-dienic electrophiles, (2Z,4Z)-1-acetoxy-2,4-heptadiene (6) and (3Z,5Z)-1-bromoctadiene (8), with ω-tert-butoxy-1-chloropentane and -butane, respectively.Optimal conditions for the reaction of 2,4-heptadiyn-1-ol and 3,5-octadiyn-1-ol to the respective Z,Z-alkadienols as precursors for the electrophiles were found.Treatment of diynols with activated zinc in aqueous alcohol provided high geometrical purity of the product (> 94percent).In both cases, copper-catalyzed cross-coupling afforded 1-tert-butoxy-7,9-dodecadiene (four stereoisomers), acetolysis of which gave the target pheromone contaminated by stereoisomers.In the case of allylic electrophile 6, the reaction occured with the loss of the initial configurational purity, whereas the use of homoyllylic bromide 8 ensured almost complete retention of the configuration of the double bonds and obtaining the target pheromone of 87percent configurational purity.