C([Li])CCC.[CH2:6]([N:13]1[CH2:19][CH2:18][CH2:17][C:16](=[O:20])[CH2:15][CH2:14]1)[C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1.[NH4+].[Cl-].[CH3:23][CH2:24][O:25][C:26]([CH3:28])=[O:27]>C1COCC1.CCCCCC.O>[CH2:6]([N:13]1[CH2:19][CH2:18][CH2:17][C:16]([CH2:28][C:26]([O:25][CH2:24][CH3:23])=[O:27])([OH:20])[CH2:15][CH2:14]1)[C:7]1[CH:8]=[CH:9][CH:10]=[CH:11][CH:12]=1To a solution of DIPA (3.1 mL) in THF (30 mL) was added dropwise a 2.6 M solution (8.6 mL) of n-butyl lithium in hexane at −70° C. After stirring at 0° C. for 40 minutes, EtOAc (2.3 mL) was added dropwise thereto at −70° C., followed by stirring for 5 minutes. A solution of 1-benzylazepan-4-one (3.6 g) in THF (10 mL) was added dropwise thereto, followed by stirring for 40 minutes. To the reaction mixture was added a saturated aqueous NH4Cl solution, followed by addition of water and extraction with EtOAc. The organic layer was washed with brine, dried over MgSO4, and then concentrated under reduced pressure. The residue was purified by medium-pressure preparative liquid chromatography (silica gel, YAMAZEN YFLC WPrep2XY, CHCl3:MeOH: aqueous ammonia) to obtain ethyl (1-benzyl-4-hydroxyazepan-4-yl)acetate (5.0 g) as a yellow oily substance.
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