The solution of potassium salt of 2-nitrophenylpyruvate B2 (100 mg, 0.36 mmol) in dry DMF (3 mL) was added dropwise over a period of 15 min, to a pre-cooled stirred solution of 2,3,4,6-tetra-O-acetyl-α-D-galactose (149 mg, 0.36 mmol) in dry DMF (2 mL) at 0° C. under nitrogen atmosphere. The temperature was gradually raised to room temperature. Reaction mixture was allowed to stir for 15 h, and the reaction was quenched with chilled, saturated aq. NaCl (25 mL). Extraction with ethyl acetate (3×30 mL), drying (MgSO4), concentration under reduced pressure, and purification by flash chromatography (SiO2, hexane-benzene-acetone-methanol, 5:4:5:1) to isolate the pure resultant compound C3 in 50% yield.
