Simultaneous Preparation of Both Enantiomers of Juvenile Hormones Labeled at C-10 with Tritium at High Specific Activity

Abstract

We report an improved method for the synthesis of high specific activity insect [10-3H]juvenile hormones (JH) I, II, and III which affords both enantiomers of each in high optical purity. A synthetic route for JH I was modified to give higher yields and purity. We increased the specific activity of the synthetic [10-3H]JHs using normal phase liquid chromatography optimized to give near baseline resolution of [10-3H]JHs and unlabeled JHs. Racemic [10-3H]JHs and their corresponding diol metabolites were enantiomerically separated using a chiral column eluted with 2-propanol:hexane. Acidic hydration of the unnatural antipode of the [10-3H]JHs gives the diol antipode with the same stereochemistry as that from epoxide hydrolase action on the natural JH antipode. The [10-3H]JH diol enantiomers can also be resolved with the same chiral column using a more polar solvent. The synthesis of high specific activity chiral ethyl ester analogs of JH I and II can also be accomplished using this synthetic route.