Potassium Hydroxide → 2'-deoxy-5-fluoro-3'-O-(4-carboxybenzyl)uridine

Potassium hydroxide (4.30 g) and 1.70 g of 4-methoxycarbonylbenzyl bromide were added to a solution of 3.00 g of 2'-deoxy-5-fluoro-5'-O-trityluridine in 200 ml of dioxane. The mixture was stirred at room temperature for a day. The reaction mixture was concentrated under a reduced pressure. To the concentrate was added 200 ml of water and the mixture was stirred at room temperature for 15 minutes. The reaction mixture was rendered acidic with acetic acid, and extracted with ethyl acetate. The organic layer was dried over magnesium sulfate and concentrated under a reduced pressure. The concentrate was dissolved in 50 ml of a 80% aqueous solution of acetic acid. The solution was heated to 100° C. for 2 hours. The solvent was distilled off and the residue was applied to silica gel column chromatography using 3% methanol-chloroform as an eluent, affording 650 mg of the title compound in a yield of 28%.