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.