1,2,4,6-Tetra-O-acetyl-3-azido-3-deoxy-D-galactopyranose 1 (167 mg, 0.45 mmol) was suspended in ethanol (5 ml), and palladium (10% on carbon, 17 mg) and HCl (1 ml of a 1M solution in diethyl ether) were added. The mixture was degassed and stirred at room temperature under a hydrogen atmosphere. After 1 h, dichloromethane was added, and the mixture was filtered through Celite and concentrated in vacuo. Half of the residue was dissolved in dichloromethane (2 ml) and pyridine (0.5 ml). 3,5-Dimethoxybenzoyl chloride (168 mg) was added, and the mixture was stirred at room temperature. After 18 h, TLC (1:1, heptane:ethyl acetate) showed the presence of a single carbohydrate product (Rf 0.2). The reaction mixture was diluted with diethyl ether (30 ml) and washed with H2SO4 (30 ml of a 10% aqueous solution), NaHCO3 (30 ml of a saturated aqueous solution), dried (MgSO4), filtered and concentrated in vacuo. The residue was purified by flash column chromatography to give 1,2,4,6-tetra-O-acetyl-3-deoxy-3-(3,5-dimethoxybenzamido)-D-galactopyranose 4 (50 mg, 44%).
