[ClH:1].COC([CH:6]1[C:11](=[O:12])[CH2:10][CH2:9][N:8]([CH2:13]C2C=CC=CC=2)[CH2:7]1)=O.[CH2:20]([OH:22])C.[H][H].[OH2:25]>[Pd]>[ClH:1].[CH3:20][O:22][C:13]([N:8]1[CH2:7][CH2:6][C:11](=[O:12])[CH2:10][CH2:9]1)=[O:25]
Into a clean, dry, nitrogen purged reactor was added 4-oxo-1-(phenylmethyl)-3-piperidinecarboxylic acid methyl ester, hydrochloride (prepared according to Preparation Five, Step A, 78.8 kg, 1.0 eq.), ethanol (416 L), water (340 L), and 10% palladium on carbon (catalyst, 7.88 kg, 0.1 kg/kg). The mixture was subjected to hydrogenation conditions of approximately 45 psig (32×103 kg/m2) of hydrogen pressure at a temperature between 25° C. to 35° C. for approximately 18 hours. After the reaction was complete, the reaction mixture was vented with nitrogen and filtered to removed the spent catalyst. The catalyst cake was washed with ethanol (150 L). The filtrate and washes were concentrated under reduced pressure to approximately 57 L. The product was crystallized by the slow addition of 2-propanol (227 L). The slurry was cooled to 10° C. to 20° C. and stirred for approximately one hour. The product was isolated by filtration, rinsed with hexanes (76 L), and dried under vacuum for approximately 24 hours to give 43.2 kg 4-oxo-1-piperidinecarboxylic acid methyl ester, hydrochloride (80.0% yield). Analysis calculated for C7H11NO3.HCl: C 43.42; H 6.25; N 7.23; found: C 43.7; H 6.59; N 7.19.
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