2,3,4,6 -tetra-O-benzyl-D-galactopyranosyl acetate (79.8 g) was dissolved in the mixed solvent of toluene (160 ml) and isopropyl ether (520 ml), and cooled to a temperature in the range of −10-0° C. An isopropyl ether solution containing 2.0 equivalents of HBr (2.8 mmole/ml, ca. 100 ml) was added to this mixture. After stirring at −10-0° C. for about 90 minutes, unreacted HBr in the reaction mixture was neutralized with 5% aqueous sodium hydrogen carbonate solution. The total volume of the mixture was separated in a separatory funnel, the aqueous layer was discarded, and the organic layer was washed twice with 10% aqueous sodium chloride solution, and concentrated under reduced pressure to give 2,3,4,6-tetra-O-benzyl-α-D-galactopyranosyl bromide (GalBr) in the form of syrup.
