CERIUM(IV)-MEDIATED HALOGENATION AT C-5 OF URACIL DERIVATIVES

Treatment of protected uracil nucleosides 1 or 2 with elemental iodine or metal halogenides and ceric ammonium nitrate (CAN) at 80 °C gave the corresponding protected 5-halouracil nucleosides 3a-f in excellent yields. Treatment of the resulting crude 3a-f with 0.1 M NaOMe/MeOH at ambient temperature gave the corresponding 5-halouridines 4a-f in high overall yields from 1 or 2. Further, 5-halouracils 9a-f were prepared in good yields by treatment of 1,3-dimethyluracil (7) or uracil (8) with elemental iodine, metal halogenides, or hydrochloric acid and CAN. Halouridines 4a-e also were obtained in good yields by treatment of unprotected uracil nucleosides 5 or 6 with halogen sources as above and CAN. © 1990, American Chemical Society. All rights reserved.