[Cl:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([CH3:8])[N:3]=1.C([Li])CCC.[O:14]=[C:15]1[CH2:20][CH2:19][N:18]([C:21]([O:23][C:24]([CH3:27])([CH3:26])[CH3:25])=[O:22])[CH2:17][CH2:16]1.[Cl-].[NH4+]>O1CCCC1.CCCCCC>[Cl:1][C:2]1[N:3]=[C:4]([CH2:8][C:15]2([OH:14])[CH2:16][CH2:17][N:18]([C:21]([O:23][C:24]([CH3:26])([CH3:25])[CH3:27])=[O:22])[CH2:19][CH2:20]2)[CH:5]=[CH:6][CH:7]=1To a solution of 0.22 ml of 2-chloro-6-methylpyridine in 12.5 ml of tetrahydrofuran was added 1.4 ml of a hexane solution containing 1.58 M n-butyl lithium at 0° C., followed by stirring the reaction mixture at 0° C. for 30 minutes. After cooling down to −78° C., a solution of 403.7 mg of tert-butyl 4-oxo-1-piperidinecarboxylate in 1 ml of tetrahydrofuran was added to the solution, followed by gradually warming up the reaction mixture to −40° C. To the reaction mixture was added saturated aqueous ammonium chloride solution, followed by extracting with chloroform. The resulting chloroform layer was washed with brine, dried over anhydrous magnesium sulfate, and filtered. The filtrate was concentrated in vacuo. The resulting residue was purified by a silica gel column chromatography (eluent: hexane/ethyl acetate=20/1−3/2) to give the title compound as a pale yellow oil.
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