Compound 30 (3.5 grams, 7.73 mmol) was coevaporated with toluene (2×) and then dissolved in anhydrous toluene (85 mL). Acetyl chloride (33 mL, 464 mmol) was added to the solution and the reaction mixture was heated to reflux and stirred under argon. After 4 hours the reaction mixture was concentrated in vacuo and the crude product was coevaporated with pyridine and then dissolved in anhydrous pyridine (42 mL). Thymidine (1.5 grams, 6.18 mmol), which had been coevaporated with pyridine and dissolved in anhydrous pyridine (42 mL), was then added to the solution containing the crude product. A catalytic amount of dimethylaminopyrimidine (DMAP) was added and the reaction mixture was stirred under argon overnight and the solvent was evaporated. The residue was redissolved in dichloromethane and washed with a 5% aqueous solution of sodium bicarbonate followed by water. The organic phase was dried (MgSO4), evaporated and purified by column chromatography (silica gel; EtOAc/hexane, 1/1) to afford 3.53 grams (84%) of compound 31 as an off-white solid. 1H NMR (300 MHz, CDCl3) δ 1.47 (s, 3H), 2.22-2.46 (m, 2H), 2.50-2.63 (m, 4H), 3.35-3.58 (m, 2H), 3.85-4.09 (m, 5H), 4.51-4.60 (m, 1H), 5.02 (dd, J=1.5, 10.4 Hz, 2H), 5.14 (dd, J=1.5, 17.3 Hz, 2H), 5.68-5.83 (m, 2H), 6.12-6.45 (m, 5H), 6.82 (d, J=9.0 Hz, 4H), 7.18-7.46 (m, 9H), 7.58 (s, 1H), 8.44 (s, 1H); Anal. Calcd for C41H44N2O7.2H2O (712.8384): C, 69.08; H, 6.79; H, 3.93. Found: C, 69.34; H, 6.44; N, 3.91.
