[H-].[Na+].[C:3]([O:9][C:10]([CH3:13])([CH3:12])[CH3:11])(=[O:8])[CH2:4][C:5]([CH3:7])=[O:6].[CH2:14]([Li])[CH2:15][CH2:16][CH3:17].ICCCC.[Cl-].[NH4+]>C1COCC1>[C:10]([O:9][C:3](=[O:8])[CH2:4][C:5](=[O:6])[CH2:7][CH2:14][CH2:15][CH2:16][CH3:17])([CH3:13])([CH3:12])[CH3:11]Anhydrous THF (200 ml) was introduced into a dried two-necked flask to which sodium hydride (60 w/w %, 2.71 g, 67.8 mmol) was added. The temperature thereof was allowed to fall to 0° C., and t-butyl acetoacetate (9.00 g, 56.9 mmol) was added dropwise thereto. The resulting mixture was stirred for 10 minutes while maintaining the temperature thereof at 0° C., and then n-butyllithium (1.6M hexane solution, 39.1 ml, 62.6 mmol) was added dropwise. After the obtained mixture was stirred for 30 minutes at 0° C., 1-iodobutane (13.6 g, 73.9 mmol) was added thereto, and then stirred for 6 hours. A saturated ammonium chloride solution was added to the obtained mixture and extracted 3 times with diethyl ether. The resulting organic layer was dried with anhydrous magnesium sulfate, filtered and concentrated. The obtained residue was purified by column chromatography (silica gel: 200 g, n-hexane/ethyl acetate=10/1) to produce the target compound (11.3 g, 73%).
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