Radiosynthesis of 3-(3-[18F]fluoropropoxy)-4-(benzyloxy)-N-[(1-dimethylaminocyclopentyl)methyl]-5-methoxybenzamide, a potential PET radiotracer for the glycine transporter GlyT-2

✍ Scribed by Haibin Tian; Rebecca Vogel; Louis Amici; Gilles Tamagnan; Ronald M. Baldwin

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: French
• Weight: 180 KB
• Volume: 49
• Category: Article
• ISSN: 0022-2135
• DOI: 10.1002/jlcr.1145

✦ Synopsis

Abstract

The recently described selective and potent GlyT2 antagonist, 4‐benzyloxy‐3,5‐dimethoxy‐N‐[(1‐dimethylaminocyclopentyl) methyl]benzamide (IC~50~=16 nM) provided an important additional tool to further characterize GlyT2 pharmacology. In order to identify an effective PET radioligand for in vivo assessment of the GlyT‐2 transporter, 3‐(3‐[^18^F]fluoropropoxy)‐4‐(benzyloxy)‐N‐((1‐dimethylaminocyclopentyl) methyl)‐5‐methoxybenzamide ([^18^F]3), a novel analog of 4‐benzyloxy‐3,5‐dimethoxy‐N‐[(1‐dimethylaminocyclopentyl) methyl]benzamide was synthesized using a one‐pot, two‐step method. The NCA radiofluorination of 1,3‐propanediol di‐p‐tosylate in the presence of K~2~CO~3~ and Kryptofix‐222 in acetonitrile gave 81% 3‐[^18^F]fluoropropyl tosylate, which was subsequently coupled with 4‐benzyloxy‐3‐hydroxy‐5‐methoxy‐N‐[(1‐dimethylaminocyclopentyl) methyl]benzamide in the same reaction vessel. Solvent extraction and HPLC (Eclipse XDB‐C8 column, 80/20/0.1 MeOH/H~2~O/Et~3~N, 3.0 ml/min) gave [^18^F]3 in 98.5% radiochemical purity. The radiochemical yield was determined to be 14.0–16.2% at EOS, and the specific activity was 1462±342 GBq/µmol. The time of synthesis and purification was 128 min. The final product was prepared as a sterile saline solution suitable for in vivo use. Copyright © 2006 John Wiley & Sons, Ltd.