[BH4-].[Na+].[CH2:3]([O:7][CH:8]([O:10][C@H:11]([CH3:19])[C:12](OCC(C)C)=[O:13])[CH3:9])[CH:4]([CH3:6])[CH3:5].CO.O>C1(C)C=CC=CC=1>[CH2:3]([O:7][CH:8]([O:10][C@H:11]([CH3:19])[CH2:12][OH:13])[CH3:9])[CH:4]([CH3:6])[CH3:5]
2.5 g of sodium borohydride was suspended at room temperature in a solution of 12.3 g of isobutyl (R)-(+)-2-(1-isobutoxyethoxy)propionate dissolved in 50 ml of toluene. Thereto was dropwise added slowly 14.4 g of methanol with stirring, so that the internal temperature of the reaction system could be kept at 34° C. or less. After the completion of the dropwise addition, the resulting mixture was stirred at room temperature for 4.5 hours. After the reaction, the reaction mixture was added 30 ml of water, followed by stirring for a while. The resulting organic layer was separated, washed with a saturated aqueous sodium chloride solution, and dried over anhydrous sodium sulfate. The resulting solution was subjected to vacuum distillation to remove the solvent, whereby was obtained 8.4 g (yield: 96%) of an oily title compound (diastereomixture). This compound was identical with the compound obtained in Example 4.
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