[F:1][C:2]1[CH:18]=[CH:17][C:16]([F:19])=[CH:15][C:3]=1[CH2:4][C:5]1[CH:6]=[C:7]([CH:12]=[CH:13][N:14]=1)[C:8]([O:10][CH3:11])=[O:9]>C(O)(=O)C.[Pt](=O)=O>[F:1][C:2]1[CH:18]=[CH:17][C:16]([F:19])=[CH:15][C:3]=1[CH2:4][CH:5]1[CH2:6][CH:7]([C:8]([O:10][CH3:11])=[O:9])[CH2:12][CH2:13][NH:14]1A mixture of methyl 2-(2,5-difluorobenzyl)isonicotinate (6.8 g, 25.83 mmol) and platinum(IV) oxide (0.293 g, 1.29 mmol) in acetic acid (68 mL) was hydrogenated in a Büchi hydrogenator at room temperature and 5 bar for 5 h. More PtO2 (190 mg) was added and the hydrogenation continued at room temperature and 5 bar for additional 80 min. The reaction mixture was filtered through Celite and the catalyst was washed with methanol. The filtrate was concentrated, the residue was dissolved in DCM, washed with satd NaHCO3 and the organic layer was dried using a phase separator. The solvent was evaporated under reduced pressure. The residue was dissolved in iso-hexane/ether and filtered. The solvents were evaporated in vacuo to yield methyl 2-(2,5-difluorobenzyl)piperidine-4-carboxylate (6.65 g, 96%). MS m/z 270 (M+H)+
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