Reaction Steps
4-Methoxyphenyl 4-O-benzyl-α-L-rhamnopyranoside (4.06 g, 11.28 mmol) and 1,1,1-triethoxyethane (2.20 g, 2.47 mL, 13.53 mmol) are dissolved in 75 mL of DMF and stirred for 50 min at 50° C. DMF was removed in vacuo. The residue was dissolved in AcOH/H2O (4:1, v/v) and stirred for 10 min at room temperature. The acetic acid is removed in vacuo and the crude product was purified by column chromatography (3:1 hexane/EtOAc) yielding 4.51 g (98%, 2 steps) of 12 as a colorless oil: [α]D: −69.4 (c=1.25, CHCl3). IR (thin film, CHCl3): 3005, 2933, 1739, 1503, 1374, 1126, 1041 cm−1. 1H NMR (CDCl3, 300 MHz) δ 1.34 (d, J=6.0 Hz, 3H), 2.19 (s, 3H), 2.41 (b, 1H), 3.44 (t, J=9.3 Hz, 1H), 3.76 (s, 3H), 3.92 (m, 1H), 4.31 (d, J=9.0 Hz, 2H), 4.74 (d, J=12.6 Hz, 2H), 4.87 (d, J=12.6 Hz, 2H), 5.29 (m, 1H), 5.36 (s, 1H), 6.82 (d, J=9.0 Hz, 2H), 6.96 (d, J=9.0 Hz, 2H), 7.33 (m, 5H). 13C NMR (CDCl3, 75 MHz) 18.1, 21.2, 55.7, 68.1, 70.0, 72.6, 75.3, 81.6, 96.3, 114.5, 117.6, 127.8, 127.8, 128.4, 138.0, 149.9, 154.9, 170.6. MALDI-HRMS: m/z [M+Na]+ calcd 425.1571, obsd 425.1565.
