Reaction Steps
To a stirred solution of 5.10 (4.7 g, 7.6 mmol) in CH3CN (30 mL) and H2O (30 mL) was added p-toluenesulfonic acid monohydrate (115 mg, 0.76 mmol). The reaction was stirred for 3 h then diluted with EtOAc and washed sequentially with saturated aqueous NaHCO3, H2O, and brine. After concentration of the organic phase in vacuo, the crude residue was purified by silica gel chromatography (50% EtOAc/petroleum ether) to afford the title compound (3.7 g, 7.3 mmol, 96%). 1H NMR (500 MHz, CDCl3): δ ppm 7.39-7.22 (m, 8H, PhH), 7.10 (d, J=7.3 Hz, 2H, PhH), 4.94, 4.67 (ABq, J=11.2 Hz, 1H each, OCH2Ph), 4.88 (d, J=9.8 Hz, 1H, H-3), 4.53 (d, J=7.8 Hz, 1H, H-1), 4.04-3.96 (m, 1H, OCHHCH2SiMe3), 3.91 (dd, J=11.7, 4.9 Hz, 1H, H-6), 3.78 (dd, J=11.7, 6.8 Hz, 1H, H-6), 3.67-3.59 (m, 1H, OCHHCH2SiMe3), 3.46 (dd, J=6.8, 5.4 Hz, 1H, H-5), 3.39 (dd, J=10.0, 7.6 Hz, 1H, H-2), 1.29 (s, 3H, Me), 1.04 (t, J=8.5 Hz, 2H, OCH2CH2SiMe3), 0.04 (s, 9H, SiMe3); 13C NMR (125 MHz, CDCl3): δ ppm 154.43, 151.15, 138.34, 129.61, 128.50, 127.81, 127.73, 126.31, 121.06, 103.64, 84.03, 79.21, 77.45, 74.92, 73.40, 68.21, 61.05, 18.73, 15.90, −1.27; HRMS calcd for C26H40NO8Si [M+NH4]+: 522.2523. found 522.2501.
