Fig. 2: 10 mg of 2,3'-anhydrothymidine (1) or 5'-O-(4,4'-dimethoxytriphenylmethyl)-2,3'-anhydrothymidine (3) dissolved in 1 ml of dry DMSO with ¹⁸F]fluoride, KHCO₃ and Kryptofix were brought to reaction at different temperatures; for (1) and (3) the reaction times were 30 and 10 minutes, respectively, as had been found to give best results in separate experiments