To a solution of 5.5 g (11.9 mmol) of the dioxolane 171 in 40 mL of THF at room temperature was added 40 mL of 4.0N HCl and the resulting solution was allowed to stir for 1 h. The mixture was neutralized with solid K2CO3, extracted with ethyl acetate and concentrated. The crude mixture was dissolved into 25 mL of CH2Cl2 to which was added 600 mg (8.8 mmol) of imidazole and 1.9 mL (7.3 mmol) of tert-butylchlorodiphenyl silane. The resulting mixture was allowed to stir overnight at room temperature and was then poured into 0.5N HCl and extracted with ethyl acetate. The organics were dried over MgSO4, filtered and concentrated. Flash chromatography (elution with 8% ethyl acetate in hexane) gave 2.12 g of the aldehyde 172 as an oil. 1H NMR consistent with the product.
