A short radiosynthesis of natural juvenile hormone III, methyl [12-3H]-(10R)-10,11-epoxyfarnesoate

A new asymmetric synthesis of natural JH III from methyl farnesoate allows introduction of tritium from sodium borotritide into the 12-methyl group. Selective allylic oxidation followed by Sharpless epoxidation of the (E)-allylic alcohol gives an epoxy alcohol (>97% e.e.), which is oxidized to the aldehyde. Sodium borotritide (65 Ci/mmol) reduction of the aldehyde is followed by tosylation, iodide displacement, and cyanoborohydride displacement to give [3H]-(10R)-JH III, specific activity 14 Ci/mmol.