[NH2:1][S:2]([C:5]1[C:6]([Cl:29])=[CH:7][C:8]([NH:22][CH2:23][C:24]2[O:25][CH:26]=[CH:27][CH:28]=2)=[C:9]([CH:21]=1)[C:10]([O:12][CH2:13][CH2:14][CH2:15][C:16]([O:18]CC)=[O:17])=[O:11])(=[O:4])=[O:3].[OH-].[Na+]>C(O)C>[NH2:1][S:2]([C:5]1[C:6]([Cl:29])=[CH:7][C:8]([NH:22][CH2:23][C:24]2[O:25][CH:26]=[CH:27][CH:28]=2)=[C:9]([CH:21]=1)[C:10]([O:12][CH2:13][CH2:14][CH2:15][C:16]([OH:18])=[O:17])=[O:11])(=[O:3])=[O:4]A mixture of ethyl 4-(5-(aminosulfonyl)-4-chloro-2-[(2-furanylmethyl)amino]benzoyloxy)butanoate (300) (0.060 mole) in ethanol (100 mL) is cooled in an ice water bath. A solution of 1.0 N sodium hydroxide (60 mL) is added dropwise with stirring, and the reaction is stirred for 12 hours at ambient temperature. The volatiles is removed by spin evaporation in vacuo. The residue is dissolved in cold water, and the solution is washed with diethyl ether. The aqueous solution is cooled in an ice bath and acidified by dropwise addition of 1.0 N hydrochloric acid solution (60 mL). The resulting solid may be collected and recrystallized to give 4-(5-(aminosulfonyl)-4-chloro-2-[(2-furanylmethyl)amino]benzoyloxy)butanoic acid.
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