(3R,4R,5R)-5-(hydroxymethyl)oxolane-2,3,4-triol

Conditions: temp:50.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: L-xylose of formula 10 (5.00 g, 33.3 mmol) and boric acid (4.53 g, 73.3 mmol) were dissolved in acetic acid (120 mL), followed by heating at 50° C. for 1 hour with stirring. Acetic anhydride (120 mL) was added thereto. The reaction mixture was heated at 50° C. for 3 days and then cooled down at room temperature, followed by extraction by using water (600 mL) and ethyl acetate (3×300 mL). The ethyl acetate extract was washed with saturated sodium_bicarbonate solution and brine, and moisture remained in the solvent was dried over magnesium sulfate. The extract was concentrated to give xylofuranose, the compound of formula 5, as a syrup (10.45 g, 32.8 mmol, 99%, α:β=1:1.8). The reaction mixture was heated at 50° C. for 3 days cooled down at room temperature followed by extraction The ethyl acetate extract was washed with saturated sodium_bicarbonate solution and brine, and moisture was dried over magnesium sulfate The extract was concentrated