CO.[CH3:3][O:4][C:5](=[O:14])[CH2:6][CH:7]1[CH2:12][CH2:11][C:10](=[O:13])[CH2:9][CH2:8]1.[BH4-].[Na+]>[Cl-].[NH4+]>[CH3:3][O:4][C:5](=[O:14])[CH2:6][C@H:7]1[CH2:12][CH2:11][C@H:10]([OH:13])[CH2:9][CH2:8]1.[CH3:3][O:4][C:5](=[O:14])[CH3:6]To a methanol (50 mL) solution of (4-oxo-cyclohexyl)-acetic acid methyl ester (4.18 g) obtained in Example (1c), sodium borohydride (1.86 g) was added in small portions at 0° C. The reaction mixture was stirred for 1 hour and diluted with a 10% aqueous ammonium chloride solution (100 mL). The organic solvent was removed using an evaporator. The remaining aqueous solution was subjected to two extractions with ethyl acetate. The organic layer was washed with saturated brine, then dried over sodium sulfate, and then concentrated to obtain trans-(4-hydroxy-cyclohexyl)-acetic acid methyl ester (2.56 g, 60%) as a colorless oil and cis-4-hydroxy-cyclohexyl)-acetic acid methyl ester (0.517 g, 12%) as a colorless oil.
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