3056-18-6

16321-99-6

3056-18-6

Synthesis of (2R,3R,4R,5R)-2-(acetyloxymethyl)-5-(2-amino-6-chloro-9H-purin-9-yl)tetrahydrofuran-3,4-diyl diacetate from (2R,3R,4R,5R)-2-(acetyloxymethyl)-5-(2,6-dichloro-9H-purin-9-yl)tetrahydrofuran-3,4-diacetic acid di-ester The general procedure was as follows: isoamyl nitrite (165 g, 1.41 mol) was dissolved in dichloromethane (500 mL) and stirred at 0 to 5 °C. Subsequently, trimethylchlorosilane (76 g, 0.70 mol) was added, followed by a solution of Compound IV (100 g, 0.234 mol) in dichloromethane (500 mL). The mixture was added dropwise to the above reaction masterbatch, and after the dropwise addition was completed, the reaction continued to be stirred at the same temperature for 1 hour. After completion of the reaction, saturated sodium sulfite solution was added for quenching and partitioning. The organic phase obtained by separation was washed sequentially with aqueous sodium bicarbonate solution and saturated brine, then dried with anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure until no fraction evaporated. The residue was recrystallized by addition of dichloromethane (100 mL) and n-heptane (350 mL) to give the yellow solid compound V, 2,6-dichloro-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purine (86 g, 82% yield).