SYNTHESIS OF (7Z,9Z)-DODECADIENYL ACETATE, A COMPONENT OF SEX-PHEROMONES OF THE LEAFROLLERS EPINOTIA AND EUCOSMA, USING CONJUGATED DIYNOLS

Two analogous routes to the title pheromones were elaborated based on organocuprate cross-coupling of Z,Z-dienic electrophiles, (2Z,4Z)-1-ac etoxy-2,4-heptadiene (6) and (3Z,5Z)-1-bromoctadiene (8), with omega-t ert-butoxy-1-chloropentane and -butane, respectively. Optimal conditio ns for the reduction of 2,4-heptadiyn-1-ol and 3,5-octadiyn-1-ol to th e respective Z,Z-alkadienols as precursors for the electrophiles were found. Treatment of diynols with activated zinc in aqueous alcohol pro vided high geometrical purity of the product (greater-than-or-equal-to 94 %). 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 al lylic electrophile 6, the reaction occurred with the loss of the initi al configurational purity, whereas the use of homoallylic bromide 8 en sured almost complete retention of the configuration of the double bon ds and obtaining the target pheromone of 87 % configurational purity.