1: [131I]-Uracil With chloro-trimethyl-silane; 1,1,1,3,3,3-hexamethyl-disilazane T=135 - 140°C; 5 - 6 h; 2: 21-deoxy-21,21-difluoro-3,5-bis-O-benzoyl-D-ribose trichloroacetimidate With trimethylsilyl trifluoromethanesulfonate in acetonitrile 3: With water in dichloromethane; acetonitrile