Simple and high radiochemical yield synthesis of 2′‐Deoxy‐2′‐[ 18 F]fluorouridine via a new nosylate precursor

We synthesized 2'‐deoxy‐2'‐[ 18 F]fluorouridine ( 7 ) as a radiotracer for positron emission tomography from a new nosylate precursor ( 6 ). This new precursor was synthesized from uridine in four steps. The overall synthetic yield was 9.4% and we have high stability of >98% purity up to 6 months at 4°C. The optimal manual [ 18 F]fluorination conditions were 30 mg of the precursor 6 in 500 µl of acetonitrile at 145°C for 15 min with 370 MBq of [ 18 F]fluoride. The [ 18 F]fluorination yield was 76.5±2.7% ( n = 3). After hydrolysis of protecting groups with 1 N HCl and purification by HPLC, the overall radiochemical yield and purity were 26.5±1.4% and 98.2±2.5%, respectively. The preparation time was 70.0±10.5 min ( n = 3 for each result). We also developed an automated method with a radiochemical yield and purity of 24.0±2.8 and 98.0±1.5% ( n = 10) using a GE TracerLab MX chemistry module. This new nosylate precursor for 2'‐deoxy‐2'‐[ 18 F]fluorouridine synthesis showed higher radiochemical yields and reproducibility than previous methods. Copyright © 2006 John Wiley & Sons, Ltd.