Reaction Steps
To a stirred mixture of triol 24 (2.9 g, 10.9 mmol) and imidazole (5.2 g, 76.8 mmol) in DMF (80 mL) at 0° C. under argon was added dropwise 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane (3.5 mL, 11.0 mmol). After the mixture was stirred at room temperature for 1 h, quenched with MeOH (15 mL) and water (100 mL) was added and the mixture was extracted with EtOAc (2×200 mL). The combined organic layers were washed with brine (40 mL) dried over Na2SO4. The solvent was removed and the residue was purified by silica gel column chromatography (EtOAc:Hexane 1:30 to 1:5) to give 25 (5.1 g, 92%) as an oil. [α]24D−105.94° (c 0.58, CHCl3); 1H NMR (500 MHz, CDCl3) δ 7.41-7.26 (m, 5H), 4.77 (d, J=12 Hz, 1H), 4.62 (d, J=12 Hz, 1H), 4.18-4.14 (m, 3H), 4.05 (dd, J=4.5, 12.0 Hz, 1H), 3.78 (dd, J=8, 12 Hz, 1H), 2.89 (m, 1H), 2.78 (d, J=2.0 Hz, 1H, OH) 1.08-0.97 (m, 28H), 0.61 (m, 1H), 0.43 (m, 1H), 0.32 (m, 1H), 0.24 (m, 1H); 13C NMR (125 MHz, CDCl3) δ 154.0, 147.3, 138.1, 128.4, 80.2, 74.2, 71.2, 71.1, 64.9, 50.1, 29.24 23.83, 17.6, 17.5, 17.4, 17.3, 17.2, 17.1, 17.0, 16.9, 16.8, 13.4, 12.9, 12.7, 12.5. 7.20; HR-MS Calcd. For (C27H46O5Si2+H)+ 507.2884. found 507.2798.
