Radiosynthesis of F-18 labeled cytidine analog 2′-fluoro-5-iodo-l-β-d-arabinofuranosylcytosine ([18F]FIAC)

We reported the synthesis of 2′-deoxy-2′-[18F]fluoro-5-iodo-1-β-d-arabinofuranosyl-5-iodo-cytosine ([18F]FIAC) with 15–20% radiochemical yield (decay corrected) in 3.5 h. 2-deoxy-2-[18F]fluoro-1,3,5-tri-O-benzoyl-α-d-arabinofuranose was prepared following literature procedures with some modifications (yield>70%). The 18F-fluorosugar was converted to 1-bromo-18F-fluorosugar, and then coupled with 5-iodocytocine silyl ether. A mixture of acetonitrile (ACN) and 1,2-dichloroethane (DCE) were employed to achieve optimum radiochemical yield and acceptable β-anomer selectivity (α/β=1/3). After hydrolyzed with sodium methoxide, the crude product was purified using HPLC to afford the β-[18F]FIAC with high radiochemical purity (⩾98%).