2,3-O-Isopropylidene-D-ribofuranose (20 g, 105.2 mmol) was dissolved in dichloromethane (200 mL) at 0° C. Triethylamine (10.9 g, 107.5 mmol) and a catalytic. amount of pyridine were added to the reaction mixture, followed by the addition of trityl chloride (27.8 g, 0.1 mol). The mixture was stirred at 0° C. for 3 h and further 12 h at room temperature. To the reaction mixture was added saturated aqueous sodium bicarbonate (80 mL) and the phases were separated. The organic phase was dried over anhydrous sodium sulfate, filtered, and the solvents were removed in vacuo. The crude product was used without further purification in the next step.
