1,2,3,4,6-Penta-O-acetyl-β-D-glucopyranose 8 (30 g, 77 mmol) was dissolved in anhydrous DCM (34 mL). 2-Methyl-5-tert-butyl thiophenol (17 mL, 92 mmol, 1.2 eq) were added under stirring. BF3.OEt2 (13.6 mL, 108 mmol, 1.4 eq) was added dropwise and the resulting yellow solution was stirred over night. After completion the solution was diluted with DCM and extracted with saturated aqueous NaHCO3 and H2O, and the organic layer was dried over MgSO4. The solvent was evaporated in vacuo and the residue was dried in high vacuum. The resulting yellow solid was purified by column chromatography on silica gel (cyclohexane/ethyl acetate) to afford 9 (33.4 g, 65.4 mmol, 85%). [α]D20=−8.0° (c=1.0, CHCl3); IR (CHCl3): 2961, 1747, 1366, 1211, 1034, 912 cm−1; 1H-NMR (400 MHz, CDCl3) δ 7.52 (1H, d, J 2.0, Ar—H), 7.25-7.10 (2H, m, Ar—H), 5.19 (1H, dd, J1J2 9.4, 1-H), 5.10-4.98 (2H, m, 4-H, 2-H), 4.64 (1H, d, J 10.6, 1-H), 4.23 (1H, dd, J1 12.2, J2 5.0, 6-Ha), 4.10 (1H, dd, J112.2, J2 1.9, 6-Hb), 3.71-3.63 (1H, m, 5-H), 2.34 (3H, s, CH3), 2.07-2.03 (6H, m, OAc), 2.00-1.96 (6H, m, OAc), 1.29 (9H, s, tBu); 13C-NMR (100 MHz, CDCl3) δ 170.8, 170.3, 169.5, 169.4 (C═O OAc), 149.8, 137.51, 131.47, 130.53, 130.2, 125.8, 87.0 (C-1), 75.9 (C-5), 74.2 (C-3), 70.3 (C-3), 68.3 (C-4), 62.4 (C-6), 31.4 (tBu), 20.89, 20.88, 20.74, 20.70 (OAc), 20.5 (CH3); HRMS (ESI): Calcd for C25H34O9S [M+Na]+ 533.1816. found 533.1832.
