[H-].[Na+].[C:3]([O:7][C:8]([N:10]1[CH2:15][CH2:14][CH:13]([OH:16])[CH2:12][CH2:11]1)=[O:9])([CH3:6])([CH3:5])[CH3:4].[Br:17][C:18]1[CH:19]=[C:20]([CH:23]=[CH:24][CH:25]=1)[CH2:21]Br>O1CCCC1>[Br:17][C:18]1[CH:19]=[C:20]([CH:23]=[CH:24][CH:25]=1)[CH2:21][O:16][CH:13]1[CH2:14][CH2:15][N:10]([C:8]([O:7][C:3]([CH3:6])([CH3:4])[CH3:5])=[O:9])[CH2:11][CH2:12]1Sodium hydride (60% dispersion in mineral oil, 3.31 g, 83 mmol) was added to an ice-cooled solution of 1-tert-butoxycarbonyl-4-hydroxy-piperidine (16.64 g, 83 mmol) in tetrahydrofuran (200 mL) and the mixture was stirred at 0° C. for 30 minutes. 3-Bromobenzyl bromide (20.66 g, 83 mmol) was added and the mixture was stirred at room temperature for 18 hours. The reaction was then quenched with water (50 mL) and concentrated in vacuo. The aqueous residue was extracted with ethyl acetate (2×100 mL) and the combined organic phases were washed with brine (100 mL), dried over magnesium sulfate and concentrated in vacuo. Purification of the residue by column chromatography on silica gel, eluting with pentane:ethyl acetate, 90:10 to 80:20, to afford the title compound as a colourless oil in 61% yield, 18.64 g.
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