Reaction Steps
Method a. A stirred solution of 209 (738 mg, 1.49 mmol) in anhydrous dichloromethane (6.4 mL) was added phenylthiotrimethylsilane (2.42 mL, 12.8 mmol) and cooled to 0° C. Trimethylsilyl triflate (0.67 mL, 3.67 mmol) was added dropwise and the solution was stirred at room temperature for 4 h. The reaction was quenched with a saturated aqueous solution of sodium hydrogen carbonate (100 mL) and extracted with dichloromethane (2×200 mL). The combined extract was dried (MgSO4) and the solvent removed by distillation under reduced pressure. The residue was purified by chromatography over silica gel with dichloromethane as eluent to give the product 210 as a clear oil (564 mg, 66%) and unreacted starting material (191 mg, 26%); Method b. A stirred solution of 211 (86 mg, 0.165 mmol) in anhydrous dichloromethane (0.49 mL) was added phenylthiotrimethylsilane (0.16 mL, 0.825 mmol) and cooled to 0° C. Trimethylsilyl triflate (0.037 mL, 0.206 mmol) was added and the solution was stirred at room temperature for 2 h. The reaction was quenched with a saturated aqueous solution of sodium hydrogen carbonate (15 mL) and the resulting mixture was extracted with dichloromethane (2×25 mL). The combined extract was dried (MgSO4) and the solvent removed by distillation under reduced pressure. The residue was purified by chromatography over silica gel with dichloromethane as eluent to give the product 210 as a clear oil (75 mg, 79%); 1H NMR (CDCl3): δ 7.47-7.19 (15 H, m, Bn, SPh), 5.48 (1 H, d, J 3.6 Hz, H-2), 5.34 (1H, dd, J 3.7, 5.2 Hz, H-1), 4.54-4.36 (7 H, m, H-3, H-5′, Bn), 3.66 (1 H, d, J 9.7 Hz, H-5), 3.48 (1 H, d, J 9.5 Hz, H-5), 2.89 (3 H, s, SO2CH3), 2.09 (3 H, s, OCCH3); 13C NMR (CDCl3): δ 169.93 (C═O), 137.69, 137.08, 132.65, 132.45, 129.15, 1.28.53, 128.52, 128.18, 128.14, 128.08, 127.91, 127.85 (Bn, SPh), 87.99, 84.35, 80.34, 75.33, 74.20, 73.67, 70.83, 69.34 (C-1, C-2, C-3, C-4, C-5, C-5′, Bn), 37.27 (SO2CH3), 20.68 (OCCH3); MS FAB: 463 (M-SPh, 100%), 595 (M+Na, 24%); Found: C, 61.17; H, 5.55; C29H32O8S2 requires C, 60.82; H, 5.63%.
