Reaction Steps
4-Methoxyphenyl 2-O-levulinoyl-α-D-fucopyranoside (2.37 g, 6.46 mmol) and dibutyl tin oxide (1.61 g, 6.46 mmol) are dissolved in 70 mL of toluene. The mixture was refluxed with a Dean-Stark trap for 2.5 h. Then it was cooled to 60° C., benzylbromide and tetrabutylammonium iodide were added and refluxed for 2 h. After cooling to room temperature the reaction mixture was diluted with water and extracted 3 times with EtOAc, dried over Na2SO4 and concentrated. The crude product was purified by column chromatography (3:2 hexane/EtOAc) yielding 2.82 g (95%, 2 steps) of 6 as a colorless oil: [α]D: +140.8 (c=0.35, CHCl3). IR (thin film, CHCl3): 3015, 1739, 1713, 1503, 1362, 1050 cm−1. 1H NMR (CDCl3, 300 MHz) δ 1.29 (d, J=6.6 Hz, 3H), 2.14 (s, 3H), 2.62 (m, 3H), 2.72 (m, 2H), 3.76 (s, 3H), 3.92 (s, 1H), 4.09 (m, 2H), 4.74 (s, 2H), 5.28 (dd, J=10.2 Hz J=3.9 Hz, 1H), 5.50 (m, 1H), 6.82 (d, J=9.0 Hz, 2H), 6.98 (d, J=9.0 Hz, 2H), 7.33 (m, 5H). 13C NMR (CDCl3, 75 MHz) 16.2, 28.1, 29.9, 37.9, 55.7, 66.2, 69.8, 70.0, 72.4, 75.6, 96.2, 114.5, 118.0, 118.2, 127.6, 127.7, 127.9, 128.5, 137.7, 150.7, 155.0, 172.0, 206.0. MALDI-HRMS: m/z [M+Na]+ calcd 481.1833, obsd 481.1824.
