Synthesis and labeling of 5′-O-(4,4′-dimethoxytrityl)-2,3′-anhydrothymidine for [18F]FLT preparation

For in vivo measurement of DNA synthesis in the patient's tumour 3'-[F-18]fluoro-3'-deoxythymidine (FLT) has been shown to be very promising. As a new labeling precursor 5'-O-(4,4'-dimethoxytrityl)-2,3'-anhydrothymidine (DNITThy) was chosen and an organic synthesis was developed including NMR and MS data for characterisation. The F-18-labeling of DMTThy can be performed within 30 minutes in radiochemical yields of almost 20% when using polar solvents such as DMF or DMSO and a temperature of 160degreesC. Hydrolysis is completed with 1N HCl at 50degreesC within 10 minutes without losses.