The main component of the sex pheromone of the smaller clear wing moth,Synanthedon tenuis, was synthesized. This iterative synthesis uses the carbocupration of acetylene, followed by the alkylation of the (Z)-alkenyl cuprate or by its reaction with ethylene oxide. (Z,Z)-3,13-octadecadien-1-yl acetate, thus obtained, is of 99.8% stereoisomeric purity. An intermediate of the synthesis was (Z)-9-tetradecene-1-yl acetate which is obtained in high yield and 99.9%Z purity.