The general procedure for the synthesis of 4,6-O-benzylidene-D-glucose from (3R,4S,5S,6R)-6-(hydroxymethyl)tetrahydro-2H-pyran-2,3,4,5-tetraol (1.00 g, 5.55 mmol) and benzaldehyde dimethylacetal (1.24 mL, 8.33 mmol) was as follows: (3R,4S,5S,6R)-6-(hydroxymethyl)tetrahydro-2H-pyran-2,3,4,5-tetraol was dissolved in N,N-dimethylformamide (11.0 mL). methyl)tetrahydro-2H-pyran-2,3,4,5-tetrol was dissolved in N,N-dimethylformamide (11.0 mL) and heated to 60 °C to dissolve it completely. Subsequently, benzaldehyde dimethyl acetal and p-toluenesulfonic acid monohydrate (10 mg) were added to the solution and the reaction mixture was stirred at 60 °C for 6 hours. During the reaction, a decompression operation was performed for 10 minutes every hour to remove volatile by-products. Upon completion of the reaction, the solvent was removed by evaporation under reduced pressure. The crude product obtained was purified by silica gel column chromatography using methanol/ethyl acetate (1:10, v/v) as eluent to collect the fraction containing 4,6-O-benzylidene-D-glucopyranose, resulting in a white crystalline product (799.5 mg, 2.98 mmol, 53.7% yield). Note: The (3R,4S,5S,6R)-6-(hydroxymethyl)tetrahydro-2H-pyran-2,3,4,5-tetraol used in the experiment was D-(+)-glucose, which was supplied by Kanto Kagaku Co.
