Simultaneous preparation of both enantiomers of juvenile hormones labeled at C-10 with tritium at high specific activity

We report an improved method for the synthesis of high specific activity insect 10-(3)H]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-(3)H]JHs using normal phase liquid chromatography optimized to give near baseline resolution of 10-(3)H]JHs and unlabeled JHs. Racemic 10-(3)H]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-(3)H]JHs gives the diol antipode with the same stereochemistry as that from epoxide hydrolase action on the natural JH antipode. The 10-(3)H]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.