High radiochemical yield synthesis of 3′-deoxy-3′-[18F]fluorothymidine using (5′-O-dimethoxytrityl-2′-deoxy-3′-O-nosyl-β-D-threo pentofuranosyl)thymine and its 3-N-BOC-protected analogue as a labeling precursor

We prepared 3'-deoxy-3'-[F-18]fluorothymidine([F-18]FLT) from 3'-O-nosyl thymidine derivative 3 or its pyrimidine ring N-BOC-protected analogue 5 and optimized [F-18] fluorination condition for a high radiochemical yield. The optimal condition for [F-18] fluorination with precursor 3 was 30 mg (41.1 mumol)/300 mul CH3CN at 130degreesC for 5 min, while precursor 5 required 34 mg (40 mumol)/300 mul CH3CN at 110degreesC for 5 min. After HPLC purification at neutral pH, we achieved high radiochemical yields of 40 +/- 5.2% and 42 +/- 5.4% (decay-corrected) within 60 min of preparation time with radiochemical purities of >97%. (C) 2003 Elsevier Science Inc. All rights reserved.