[H-].[Na+].CN(C)C=O.[OH:8][CH:9]1[CH2:14][CH2:13][CH2:12][N:11]([C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[O:16])[CH2:10]1.[F:22][C:23]1[CH:24]=[C:25]([CH:28]=[CH:29][C:30]=1[F:31])[CH2:26]Br>CCCCC>[F:22][C:23]1[CH:24]=[C:25]([CH2:26][O:8][CH:9]2[CH2:14][CH2:13][CH2:12][N:11]([C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[O:16])[CH2:10]2)[CH:28]=[CH:29][C:30]=1[F:31]To sodium hydride (60% w/w dispersion in oil, 0.62 g, 16.4 mmol) washed in pentane was added N,N-dimethylformamide (20 ml) and then 1,1-dimethylethyl 3-hydroxypiperidine-1-carboxylate (Preparation 117, 3.0 g, 14.9 mmol). The reaction mixture was stirred for 1 h, before adding 3,4-difluorobenzyl bromide (2.0 ml, 16.4 mmol) and stirring the reaction mixture for 18 h. The reaction mixture was concentrated in vacuo and the crude residue was dissolved in dichloromethane and washed with brine and dried (MgSO4) before concentrating in vacuo. The crude residue was purified by flash chromatography to give the title compound (4.58 g, 94%).
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