To a stirred solution of D-arabinose (50 g, 0.33 mol) in DMF (500 mL) was added imidazole (45 g, 0.66 mol) and tert-butylchlorodiphenylsilane (109 g, 0.4 mol). After being stirred at room temperature for 2 hours, the resulting solution was diluted with EtOAc (2000 mL), washed with water, brine and dried over Na2SO4. The organic layer was concentrated in vacuo and the residue was purified by column chromatography on silica gel (eluting with 1:11 EtOAc in petroleum ether) to afford 33 g of (2R,3S,5R)-5-[[tert-butyl(diphenyl)silyl]oxymethyl]tetrahydrofuran-2,3,4-triol (compound 25a).
