Dichloromethane → (1R,3R,4R,7R)-7-Benzyloxy-1-(4,4'-dimethoxytrityloxymethyl)-3-(Thymin-1-yl)-2,5-Dioxabicyclo[2.2.1]Heptane

Beteiligte Stoffe

Reaktionsschritte

To a solution of nucleoside 7 (4.22 g, 5.06 mmol) in anhydrous DMF (25 cm3) at 0° C. was added a 60% suspension of sodium hydride in mineral oil (w/w, 0.607 g, 1 5.7 mmol, added in four portions during 20 min) and the reaction mixture was stirred at room temperature for 25 h, cooled to 0° C. and diluted with dichloromethane/pyridine (100 cm3, 99.5:0.5, v/v). A saturated aqueous solution of sodium hydrogen carbonate (120 cm3) was added whereupon extraction was performed using dichloromethane (75 cm3×2). The combined organic phase was washed with saturated aqueous solutions of sodium hydrogen carbonate (60 cm3×3) and brine (40 cm3×3), dried (Na2SO4) and evaporated to dryness under reduced pressure. The residue was purified by silica gel column chromatography using dichloromethane/methanol/pyridine (0.5–1.5% methanol; 0.5% pyridine, v/v/v) as eluent yielding nucleoside 8 (3.2 g, 96%) as a white solid material after evaporation of the solvents under reduced pressure.

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