TBDMS-Cl (184 mg, 1.22 mmol), and imidazole (131 mg, 1.95 mmol) were added to a stirred solution of the compound D7 (256 mg, 0.488 mmol) in THF (2.5 mL). The reaction mixture was stirred at rt for 15 h. The crude mixture was partitioned between Et2O and aq. sat. NH4Cl. The org. layer was dried over MgSO4, filtered, and the solvents were removed under reduced pressure. The crude oil was dissolved in THF (4.5 mL), MeOH (0.7 mL), and water (0.7 mL), and K2CO3 (34 mg, 0.024 mmol) was added. The mixture was stirred at rt for 3 h. The mixture was partitioned between Et2O and aq. sat. NH4Cl, and the aq. layer was extracted once more with Et2O. The combined org. extracts were dried over MgSO4, filtered, and the solvents were removed in vacuo to yield the title compound (0.34 g, quantitative yield) as a yellow oil that was not further purified. LC-MS: tR=1.10 min, ES+: 640.50.
