The reaction of the 5-vinyluracil derivative (I) with NBS and NaN3 in dimethoxyethane gives the 1-azido-2-bromoethyluracil derivative (II), which is treated with potassium tert-butoxide in THF to yield the 1-azidovinyluracil compound (III). Finally, this compound is debenzoylated with ammonia in methanol to afford the target dihydroxylated uracil derivative.