No-carrier added synthesis of 18F-labelled nucleosides using Stille cross-coupling reactions with 4-[18F]fluoroiodobenzene

The radiosyntheses of 5-(4′-[18F]fluorophenyl)-uridine [18F]-11 and 5-(4′-[18F]fluorophenyl)-2′-deoxy-uridine [18F]-12 are described. The 5-(4′-[18F]fluoro-phenyl)-substituted nucleosides were prepared via a Stille cross-coupling reaction with 4-[18F]fluoroiodobenzene followed by basic hydrolysis using 1 M potassium hy-droxide. The Stille cross-coupling reaction was optimized by screening various palladium complexes, additives and solvents. By using optimized labelling conditions (Pd2(dba)3/CuI/AsPh3 in DMF/dioxane (1:1), 20 min at 65°C), 550 MBq of [4-18F]fluoroiodobenzene could be converted into 120 MBq (33%, decay-corrected) of 5-(4′-[18F]fluorophenyl)-2′-deoxy-uridine [18F]-12 within 40 min, including HPLC purification. Copyright © 2004 John Wiley & Sons, Ltd.