500 mg of 2'-deoxy-3',5'-di-O-acetyl-5-fluorouridine and 0.76 ml of triethylamine were added to 20 ml of dry ether, and the resulting mixture was stirred. To the mixture was added 710 mg of 2-methylbenzoyl chloride, and the resulting mixture was stirred at room temperature for 6 hours. The mixture was subjected to thin-layer chromatography on silica gel, together with the product in Example 1 as an authentic compound, using a mixed solvent of chloroform/methanol (39/1), thereby indicating that in the mixture was formed 2'-deoxy-3',5'-di-O-acetyl-5-fluoro-3-(2-methylbenzoyl)uridine. The Rf value was 0.62.
