The sex pheromones produced by females of the lesser peachtree borer,Synanthedon pictipes (Grote and Robinson), and the peachtree borer,Synanthedon exitiosa (Say), (E,Z)- and (Z,Z)-3,13-octadecadien-1-ol acetate, respectively, were synthesized from 1,8-dichlorooctane, lithium acetylide, and ethylene oxide. In the course of the synthesis a new carbon-oxygen cleavage reaction of homopropargylic acetals was found, and the stereochemistry of the dissolving metal reductions of acetylenic alcohols was investigated.