Reaction Steps
A mixture of galactosyl donor 3 (0.18 g, 0.35 mmol), glucosyl acceptor 4 (0.20 g, 0.27 mmol), and 4 Å MS (0.4 g) in dichloromethane (5 mL) was stirred at room temperature under an atmosphere of argon for 30 min. The reaction mixture was cooled (0° C.) and then NIS (78.7 mg, 0.35 mmol) and TMSOTf (7.0 μL, 0.035 mmol) were sequentially added. The reaction mixture was stirred for 10 min and then quenched with pyridine (50 μL). The reaction mixture was diluted with dichloromethane (5 mL) filtered through celite and washed with aqueous solution of Na2S2O3 (15%, 10 mL), NaHCO3 (sat., 7 mL), and water (7 mL). The organic layer was dried (MgSO4), filtered and the filtrate concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/ethyl acetate, 4/1, v/v) to give 5 (0.28 g, 87%) as a clear oil. Rf=0.35 (hexane/ethyl acetate, 4/1, v/v). [α]25D=+46.3 (c 1.05, CHCl3); 1H (500 MHz, CDCl3): δ 7.69-6.92 (m, 37H, aromatic), 5.28 (dd, 1H, J1′,2′=8.0 Hz, J2′,3′=8.5 Hz, H-2′), 5.19 (d, 1H, JHaHb=11.0 Hz, CHaHb, napthylmethyl), 5.11-5.08 (bd, 2H, CH2-LCbz), 4.86 (d, 1H, CHH, OBn), 4.74-4.72 (bd, 2H, CHaHb, napthylmethyl, H—), 4.63-4.55 (dd, 2H, CH2, OBn), 4.44-4.42 (bd, 2H, CH2-LBn), 4.37-4.31 (dd, 3H, CH2, OBn), 4.28 (d, 1H, J1′,2′=8.0 Hz, H-1′), 3.89-3.81 (m, 5H, H-4′, H-3, H-4, CH2, OBn), 3.69-3.67 (m, 1H, H-5′), 3.59-3.50 (m, 3H, H-5, H-6a, b), 3.23-3.14 (m, 6H, H-2, H-3′, H-6′a, b, 3×CHH-L), 3.04-3.02 (m, 1H, CHH-L), 1.88 (s, 3H, COCH3), 1.52-1.48 (m, 4H, 2×CH2-L), 1.27-1.18 (m, 2H, CH2-L). 13C (75 MHz, CDCl3): δ 169.55, 138.97, 138.27, 138.19, 138.05, 136.62, 133.53, 133.10, 128.77, 128.68, 128.65, 128.52, 128.47, 128.28, 128.24, 128.15, 128.10, 128.07, 127.95, 127.92, 127.82, 127.80, 127.76, 127.51, 126.51, 125.82, 101.03 (C-1′), 97.99 (C-1), 80.70, 78.01, 77.68, 77.46, 77.26, 76.83, 75.21, 74.84, 73.81, 73.54, 73.35, 72.74, 72.17, 71.89, 70.82, 68.42, 68.04, 67.80, 67.39, 63.23, 29.24, 23.52, 21.32. HR-MALDI-TOF/MS (m/z) calcd for C73H78N4O13[M+Na]+: 1241.5455; found: 1241.5457.
