[C:1]([O:5][C:6]([N:8]1[C:12](=[O:13])[CH2:11][C:10]2([CH2:18][CH2:17][CH2:16][CH2:15][CH2:14]2)[CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[Li+].[OH-].CCCCCC.BrC1C=CC=C([OH:34])C=1C>C1COCC1.C(OCC)(=O)C>[C:1]([O:5][C:6]([NH:8][CH2:9][C:10]1([CH2:11][C:12]([OH:34])=[O:13])[CH2:18][CH2:17][CH2:16][CH2:15][CH2:14]1)=[O:7])([CH3:4])([CH3:3])[CH3:2]
3-oxo-2-aza-spiro[4.5]decane-2-carboxylic acid tert-butyl ester (253 mg, 1 mmol) was dissolved in THF (5 ml) and an aqueous solution of 1N LiOH (72 mg/3 ml, 3 molequivalents) was added thereto. The mixture was stirred at 25° C. for 6 hours while monitoring the progress of the reaction by TLC, using a 6:4 hexane:ethyl acetate mixture as eluent and bromocresol for developing the TLC plate. Reaction completion was indicated by the appearance of a more polar spot while the starting material gradually disappeared from the middle of the TLC plate. Thereafter, the THF was evaporated under reduced pressure and the basic aqueous residue was acidified by the addition of 15 drops of concentrated HCl (pH 3) and extracted with ethyl acetate. The aqueous layer was washed with ethyl acetate and the combined organic layer was washed with water, dried over NaSO4 and evaporated under reduced pressure to give [1-(tert-butoxycarbonylamino-methyl)-cyclohexyl]-acetic acid (228 mg, 84% yield) as a colorless solid.
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