C([O:3][C:4](=[O:21])[CH:5]=[C:6]1[CH2:11][CH2:10][CH:9]([CH2:12][NH:13][C:14]([O:16][C:17]([CH3:20])([CH3:19])[CH3:18])=[O:15])[CH2:8][CH2:7]1)C.[OH-].[Na+]>CO.C1COCC1>[C:17]([O:16][C:14]([NH:13][CH2:12][CH:9]1[CH2:8][CH2:7][C:6](=[CH:5][C:4]([OH:21])=[O:3])[CH2:11][CH2:10]1)=[O:15])([CH3:20])([CH3:18])[CH3:19]To a solution of [4-(tert-Butoxycarbonylamino-methyl)-cyclohexylidene]-acetic acid ethyl ester (0.518 g, 1.74 mmol) in MeOH (16 mL) and THF (4 mL) was added sodium hydroxide (9.0 mL, 1N, 9.0 mmol) and the reaction stirred at RT for 23 hr. The reaction was quenched with H2O and extracted with EtOAc (2×). The aqueous layer was acidified to pH ˜1 with 1N HCl and extracted with EtOAc (3×). The combined organic layers were dried over Na2SO4, filtered, and concentrated in vacuo to provide 0.300 g (64%) of product. ESI-MS m/z 270 (MH)+.
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