[C:1]([O:5][C:6](=[O:26])[CH2:7][C@H:8]1[CH2:13][C@@H:12]([CH2:14][O:15]C(=O)C2C=CC=CC=2)[O:11][C:10]([CH3:25])([CH3:24])[O:9]1)([CH3:4])([CH3:3])[CH3:2].[OH-].[Na+].Cl>CO>[C:1]([O:5][C:6](=[O:26])[CH2:7][C@H:8]1[CH2:13][C@@H:12]([CH2:14][OH:15])[O:11][C:10]([CH3:25])([CH3:24])[O:9]1)([CH3:2])([CH3:4])[CH3:3]To a solution of 3.64 g (10 mmol) of the 2-[(4R,6S)-2,2-dimethyl-6-benzoyloxymethyl-1,3-dioxan-4-yl]acetic tert-butyl ester produced in Example 26 in methanol (36 mL) was added 10 mL of 1N-aqueous sodium hydroxide solution, and the mixture was stirred at room temperature for 2 hours. This reaction mixture was adjusted to pH 7 by gradual addition of 1N-hydrochoric acid under ice-cooling. The methanol was then distilled off under reduced pressure and the residual aqueous solution was extracted with 2 portions of methylene chloride, 70 mL each. The organic layer was dehydrated over anhydrous sodium sulfate and the solvent was distilled off under reduced pressure to give a colorless oil. This residue was purified by silica gel column chromatography (Kieselgel 60, product of Merck; hexane:acetone=5:1) to give 2.34 g of 2-[(4R,6S)-6-(hydroxymethyl)-2,2-dimethyl-1,3-dioxan-4-yl]acetic tert-butyl ester (white solid). Yield 90%.
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