Synthesis of carrier-free tritium-labeled queen bee pheromone

A short synthesis of [4,5-(3)H2] (E)-9-oxo-2-decenoic acid (ODA), a high-specific-activity tritium-containing isotopomer of the queen bee pheromone, is described. Catalytic tritiation of the ketal of ethyl 9-oxo-4-decenoate introduces tritium into two positions, one of which is completely unactivated. Subsequent transformation by selenation, oxidation, and hydrolysis affords the labeled 9-ODA at >60 Ci/mmol. The material is suitable for biochemical studies of binding and catabolism in ovarian, antennal, and other target tissues.