Synthesis of 131I, 125I, 123I and 82Br labelled 5-halo-1-(2-deoxy-2-fluoro-β-d-arabinofuranosyl)uracils

“Carrier-added” and “no-carrier added” [123I, 125I, 131I]5-iodo-1-(2-deoxy-2-fluoro-β-d-arabinofuranosyl)uracils 2a–c were synthesized by reaction of 1-(2-deoxy-2-fluoro-β-d-arabinofuranosyl)uracil 1 with [123I, 125I, 131I]sodium iodide in the presence of nitric acid with a 90 min reaction time at 115°C. In the “carrier-added” reactions 2a, 2b and 2c were obtained in 90, 89.9 and 90% isolated radiochemical yield with a specific activity of 600, 104 and 111 GBq mmol−1 respectively, in greater than 99% radiochemical purity. Alternatively, reaction of 1 with [82Br]NH4Br and N-chlorosuccinimide gave [82Br]FBrAU 3 in 85.6% isolated radiochemical yield with a specific activity of 0.14 GBq mmol−1. The short reaction time of 60 min for the bromination reaction makes it a suitable method for incorporation of the positron emitter 75Br (t12, 95.5 min).