To a mixture of 3-(2,3,4-tri-O-benzyl-α-L-fucopyranosyl)propanal (800 mg, 1.69 mmol) and 2-aminoethyl 3,4,6-tri-O-acetyl-2-(acetylamino)-2-deoxy-β-D-glucopyranoside (987 mg, 2.53 mmol) in CH2Cl2 (15 mL) was added acetic acid (29 μL, 0.506 mmol) and sodium triacetoxyborohydride (893 mg, 4.21 mmol). After stirring at rt overnight, the reaction mixture was concentrated and the residue was taken up in EtOAc (70 mL), washed with sat'd NaHCO3 (2×100 mL), brine (30 mL), dried over Na2SO4, filtered and concentrated. The residue was taken up in CH3OH (8 mL), to which NaOCH3 (27 mg, 0.506 mmol) was added. After stirring at rt for 2 hr, the resulting mixture was concentrated and the residue was purified by flash chromatography on C18 reverse phase silica gel (120 g), eluting with 5-100% AcCN in water to give the title compound. 1H NMR (CDCl3, 400 MHz) δ 1.30 (d, J=6.6, 3H), 1.50 (m, 1H), 1.60 (m, 1H), 1.68 (m, 1H), 2.02 (s, 3H), 2.64 (m, 2H), 2.81 (m, 2H), 3.39 (m, 1H), 3.57 (m, 2H), 3.69 (m, 1H), 3.78-3.85 (m, 4H), 3.92 (m, 2H), 4.00 (m, 2H), 4.45 (d, J=7.7, 1H), 4.52 (d, J=11.9, 1H), 4.62 (d, J=11.8, 1H), 4.68 (d, J=12.1, 1H), 4.79 (d, J=12.0, 2H), 7.28-7.38 (m, 15H), 7.65 (s, 1H); [M+H/e]+=723.3925.
