Reaction Steps
A solution of phenyl 1-thio-β-D-galactopyranoside (2.1) (3.00 g, 11.0 mmol) and dibutyltin oxide (3.00 g, 12.1 mmol) in dry methanol (80 ml) was refluxed for 2 hours to produce a clear mixture. The solvent was then evaporated under reduced pressure. The resultant residue was dissolved in dry benzene (80 mL) followed by the addition of Bu4NBr (3.90 g, 12.11 mmol) and BnBr (1.3 ml, 12.1 mmol). The mixture was refluxed overnight. After cooling to room temperature, the mixture was concentrated and the residue was purified by silica gel chromatography (50% EtOAc/petroleum ether) to afford the title compound (2.71 g, 7.48 mmol, 67%). 1H NMR (400 MHz, CDCl3): δ 7.60-7.20 (m, 10H, PhH), 4.77, 4.68 (ABq, J=11.7 Hz, 1H each, OCH2Ph), 4.59 (d, J=9.5 Hz, 1H, H-1), 4.08 (d, J=2.6 Hz, 1H, H-4), 3.76 (dd, J=9.5, 9.5 Hz, 1H, H-2), 3.75 (dd, J=11.4, 5.8 Hz, 1H, H-6), 3.70 (dd, J=11.4, 5.8 Hz, 1H, H-6), 3.50 (dd, J=5.8, 5.8 Hz, 1H, H-5), 3.41 (dd, J=9.5, 2.6 Hz, 1H, H-3); 13C NMR (100 MHz, CDCl3): δ 131.0, 128.6, 128.1, 127.8, 127.4, 126.8, 89.1, 82.5, 79.2, 71.5, 69.0, 66.2, 61.4; HRMS calcd for C19H26O5SN [M+NH4]+: 380.1532. found 380.1527.
