Preparation of 3′‐deoxy‐3′‐[18F]fluorothymidine ([18F]FLT) in ionic liquid, [bmim][OTf]

Although 3′‐deoxy‐3′‐[¹⁸F]fluorothymidine ([¹⁸F]FLT) is a prospective radiopharmaceutical for the imaging of proliferating tumor cell, it is difficult to prepare large amount of [¹⁸F]FLT. We herein describe the preparation of [¹⁸F]FLT in an ionic liquid, [bmim][OTf] (1‐butyl‐3‐methyl‐imidazolium trifluoromethanesulfonate). At optimized condition, [¹⁸F]fluorinationin ionic liquid with 5 µl of 1 M KHCO₃ and 5 mg of the precursor yielded 61.5 ± 4.3% (n=10). Total elapsed time was about 70 min including HPLC purification. The rapid synthesis of [¹⁸F]FLT can be achieved by removing all evaporation steps. Overall radiochemical yield and radiochemical purity were 30 ± 5% and >95%, respectively. This method can use a small amount of a nitrobenzenesulfonate precursor and can be adapted for automated production. Copyright © 2006 John Wiley & Sons, Ltd.