Radiosynthesis of [¹¹C]docetaxel

Docetaxel (Taxotere®) is an accepted chemotherapeutic agent for the treatment of breast cancer and non-small cell lung cancers. A potential means of predicting response is measuring tumor uptake of [¹¹C]docetaxel using Positron Emission Tomography (PET). The synthetic approach to introduce the ¹¹C isotope in the 2-benzoyl moiety of docetaxel unfortunately was unsuccessful. The radiosynthesis of [¹¹C]docetaxel (6b, Scheme 1), with the ¹¹C isotope in the BOC moiety, was however, successful using a second synthetic approach. It started with the reaction of [ ¹¹C]tertbutanol with 1,2,2,2-tetrachloroethyl chloroformate to give [¹¹C]tert-butyl-1,2,2,2-tetrachloroethyl carbonate in a good overall yield (62 ± 9%). In the final step, the [¹¹C]tert- butoxycarbonylation of the free amine of docetaxel gave [¹¹C] docetaxel 6b in a satisfactory decay corrected yield of 10 ± 1% (from [¹¹C]CO₂).