[CH3:1][N:2]1[CH2:13][CH2:12][C:5]2([NH:9]C(=O)N[C:6]2=[O:11])[CH2:4][CH2:3]1.[OH2:14].O.O.O.O.O.O.O.[OH-].[Ba+2].[OH-]>O>[NH2:9][C:5]1([C:6]([OH:11])=[O:14])[CH2:4][CH2:3][N:2]([CH3:1])[CH2:13][CH2:12]11 -methylpiperidine-4-spiro-5'-hydantoin (9.75 g., 0.0533 mole) and barium hydroxide octahydrate (28.8 g., 0.00913 mole) in water (150 ml.) were heated at 160° C. in an autoclave for three hours. The contents of four such batches were combined and the precipitated barium carbonate was filtered off. The filtrate was neutralized with solid carbon dioxide and the precipitate was removed by filtration. The filtrate was concentrated to a small volume to give 4-amino-1-methylpiperidine-4-carboxylic acid (32.0 g., 95% yield), m.p. 275°-280° C. (dec.).
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