[O:1]=[C:2]1[CH2:7][CH2:6][CH:5]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[CH2:4][CH2:3]1.O.[CH2:14](OCC)C>>[OH:1][C:2]1([CH3:14])[CH2:7][CH2:6][CH:5]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[CH2:4][CH2:3]1To a solution of 25.0 g of ethyl 4-oxocyclohexanecarboxylate in 500 ml of diethyl ether, 150 ml of 1.6N methyl lithium-ether solution was added at −60° C. in nitrogen atmosphere, followed by 30 minutes' stirring at −60° C. Water was added to the reaction liquid which then was extracted with ethyl acetate. The ethyl acetate layer was washed with saturated brine, dried on anhydrous magnesium sulfate and the solvent was distilled off. The residue was separated and purified on silica gel column chromatography (ethyl acetate/hexane=1/4) to provide 22.7 g of the title compound.
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