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

For in vivo measurement of DNA synthesis in the patient"s tumour 3"-[18F]fluoro-3"-deoxythymidine (FLT) has been shown to be very promising. As a new labeling precursor 5"-O-(4,4"-dimethoxytrityl)-2,3"-anhydrothymidine (DMTThy) was chosen and an organic synthesis was developed including NMR and MS data for characterisation. The 18F-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 160 °C. Hydrolysis is completed with 1N HCl at 50 °C within 10 minutes without losses.