[Li]CCCC.CCCCCC.[CH2:12]([O:19][C:20]1[CH:25]=[CH:24][C:23](Br)=[CH:22][N:21]=1)[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1.[CH:27](=[O:30])[CH2:28][CH3:29].[Cl-].[NH4+]>C1COCC1>[CH2:12]([O:19][C:20]1[N:21]=[CH:22][C:23]([CH:27]([OH:30])[CH2:28][CH3:29])=[CH:24][CH:25]=1)[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1In a nitrogen atmosphere at −78° C., 2.71 M n-BuLi/hexane solution (18.8 mL) was dropwise added to a THF solution of 2-(benzyloxy)-5-bromopyridine (12.2 g, 46.2 mmol) synthesized according to the method described in a reference (J. Org. Chem., 1995, Vol. 60, p. 1408), and stirred at −78° C. for 1 hour. At −78° C., propionaldehyde (4.3 mL) was dropwise added, and stirred at −78° C. for 30 minutes and then at room temperature for 3 hours. Aqueous saturated ammonium chloride solution was added to the reaction liquid, and extracted with ethyl acetate. The organic layer was washed with saturated saline, then dried with magnesium sulfate and concentrated. This was purified by silica gel column chromatography to obtain the intended compound (7.15 g, 64%) as a yellow oil.
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