N-(2-Hydroxyethyl)phthalimide (277 g, 1.45 mol) was slowly added to a solution of borane in tetrahydrofuran (1 M, 600 mL), with stirring. Hydrogen gas evolved as the solid dissolved. Once the rate of gas evolution subsided, the solution was placed in a 2 L stainless steel bomb. 2,2′-Anhydro-5-methyluridine (60 g, 0.25 mol) and sodium bicarbonate (120 mg) were added and the bomb was sealed. After 30 minutes, the bomb was vented and placed in an oil bath and heated to 150° C. internal temperature for 24 h. The bomb was cooled to room temperature and opened. TLC (ethyl acetate-methanol; 95:5) revealed the disappearance of starting material. The crude solution was concentrated and the residue was purified by chromatography on silica gel starting with ethyl acetate to remove the excess phthalimide reagent, followed by ethyl acetate-methanol (95:5) to elute 2 (22.2 g, 20.6%).
