Methy1 3H] thymine was synthesized from 5 formyluracil by the “two-stepmethod”.As the first step
5 [hydroxymethy1 3H] hydroxymethyluracil was prepared with specific radioactivity of 1.6PBq/mol.Then [methy1 3H]thymine was synthesizedvia enzymatic reaction with specific radioactivity of 2.2PBq/mol.The radiochemical purity of the product was over 95%.