Synthesis of [ 18 F]‐labeled 2′‐deoxy‐2′‐fluoro‐5‐methyl‐1‐ β ‐D‐arabinofuranosyluracil ([ 18 F]‐FMAU)

Synthesis of 2′‐deoxy‐2′‐[ 18 F]fluoro‐5‐methyl‐1‐ β ‐D‐arabinofuranosyluracil ([ 18 F]‐FMAU) is reported. 2‐Deoxy‐2‐[ 18 F]fluoro‐1,3,5‐tri‐O‐benzoyl‐ α ‐D‐arabinofuranose 2 was prepared by the reaction of the respective triflate 1 with tetrabutylammonium[ 18 F]fluoride. The fluorosugar 2 was converted to its 1‐bromo‐derivative 3 and coupled with protected thymine 4 . The crude product mixture ( 5a and 5b ) was hydrolyzed in base and purified by HPLC to obtain the radiolabeled FMAU 6a . The radiochemical yield of 6a was 20–30% decay corrected (d.c.) in four steps with an average of 25% in four runs. Radiochemical purity was >99% and average specific activity was 2300 mCi/μmol at the end of synthesis (EOS). The synthesis time was 3.5–4.0 h from the end of bombardment (EOB). Copyright © 2002 John Wiley & Sons, Ltd.