A novel compound cis-6-undecene-1-chloride is prepared by reacting cis-3-octene-1-chloride with metallic magnesium to give a Grignard reagent of the chloride and then reacting the Grignard reagent with 1-bromo-3-chloropropane in the presence of a lithium copper chloride as a catalyst. The inventive compound is a useful intermediate compound for the synthetic preparation of several kinds of so-called sexual pheromone compounds of noxious insects. As an example of such sexual pheromone compounds. the synthetic preparation of cis-9-tetradecenyl acetate is described.