The invention is a novel method and precursor for preparing radiolabeled nucleosides. In particular, the invention is useful for preparing 3'-[18F]fluorothymidine. The method uses an enol group that is attached to the 2-position on the pyrimidine ring. The enol group attenuates thymidines activity so that the thymidine is easily radiolabeled in short number of steps with good yield.
