1,2,3,4,6-penta-O-acetyl-galactopyranose (1.17 g, 3 mmol) was dissolved in dry CH2Cl2 (15 ml), then trimethylsilyl azide (416 mg, 3.6 mmol) and SnCl4 (0.18 ml) were added under nitrogen. The mixture was stirred at room temperature for 24 hours. The reaction mixture was subsequently diluted with CH2Cl2 (40 ml), dried over MgSO4 and evaporated. The residue was purified by chromatography using hexane/EtOAc 8:7 v/v as the mobile phase to give 2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl azide (1.05 g, 94%).
