Abstract: | 1‐(2′‐deoxy‐2′‐fluoro‐β‐D‐arabinofuranosyl)‐methyl‐11C]thymine (11C]FMAU) 11C]‐ 1 was synthesised via a palladium‐mediated Stille coupling reaction of 1‐(2′‐deoxy‐2′‐fluoro‐β‐D‐arabinofuranosyl)‐5‐(trimethylstannyl)uracil 2 with 11C]methyl iodide in a one‐pot procedure. The reaction conditions were optimized by screening various catalysts and solvents, and by altering concentrations and reaction temperatures. The highest yield was obtained using Pd2(dba)3 and P(o‐tolyl)3 in DMF at 130°C for 5 min. Under these conditions the title compound 11C]‐ 1 was obtained in 28±5% decay‐corrected radiochemical yield calculated from 11C]methyl iodide (number of experiments=7). The radiochemical purity was >99% and the specific radioactivity was 0.1 GBq/μmol at 25 min after end of bombardment. In a typical experiment 700–800 MBq of 11C]FMAU 11C]‐ 1 was obtained starting from 6–7 GBq of 11C]methyl iodide. A mixed 11C/13C synthesis to yield 11C]‐ 1 /(13C)‐ 1 followed by 13C‐NMR analysis was used to confirm the labelling position. The labelling procedure was found to be suitable for automation. Copyright © 2002 John Wiley & Sons, Ltd. |