To a mixture of 50 ml of benzene and 50 ml of dioxane were added 1.00 g of 2'-deoxy-5-fluoro-5'-O-trityluridine, 0.30 ml of benzyl bromide and 0.23 g of potassium hydroxide powder, and the mixture was refluxed for 25 hours. The insolubles were removed by filtration and the filtrate was concentrated and the concentrate was dissolved in 5 ml of 80% acetic acid. The solution was left to stand at 80° C. for 2 hours. The solvent was distilled off and the residue was placed on a silica gel column to conduct a gradient elution using chloroform and mixtures of methanol (up to 2%) and chloroform. The fractions corresponding to 3'-O-benzyl-2'-deoxy-5-fluorouridine were collected and concentrated. The concentrate was recrystallized from ethanol, giving 0.14 g of the title compound in a yield of 20%.
