To a solution of 2.58 g (11.6 mmol) of alcohol 170 and 1.19 g (17.5 mmol) of imidazole in 50 mL of CH2Cl2 was added 3.4 mL (13.1 mmol) of tert-butylchlorodiphenyl silane and the resulting mixture was allowed to stir at room temperature for 1 h. The mixture was then diluted with ethyl acetate and washed with 0.5N HCl. The organic layer was dried over MgSO4, filtered and concentrated. Flash chromatography (elution with 5% ethyl acetate in hexane) afforded 5.5 g of 171. 1H NMR consistent with the product.
