A novel and convenient procedure for synthesizing 3′, 5′-dithiothymidine was described. In this procedure, DBU was used to form the intramolecular ring of 2, 3′-anhydrothymidine and then the thioacetic acid was used as solvent as well as the nucleophilic reagent to produce S-acetyl-3′-thiothymidine. A very efficient deprotection step was applied to afford the target compound, which can avoid the oxidization of the thiol groups. And the key ...