[C:1]([O:5][C:6]([N:8]1[C:16]2[C:11](=[CH:12][CH:13]=[CH:14][CH:15]=2)[CH:10]([C:17]([O:19]CC)=[O:18])[CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[OH-].[Na+]>CO.O>[C:1]([O:5][C:6]([N:8]1[C:16]2[C:11](=[CH:12][CH:13]=[CH:14][CH:15]=2)[CH:10]([C:17]([OH:19])=[O:18])[CH2:9]1)=[O:7])([CH3:4])([CH3:2])[CH3:3]A mixture of 0.7 g of ethyl 1-(tert-butoxycarbonyl)indoline-3(R,S)-carboxylate (Example 97d) in 18 ml of methanol/water (1:1) and 2.9 ml of a 1N sodium hydroxide solution is stirred at 50° C. for 3 h. After the methanol has been removed in vacuo, the aqueous phase is brought to pH 2 and extracted with ethyl acetate. Customary further working up gives the title compound as a white solid: Rf (hexane/ethyl acetate/glacial acetic acid (75:25:1))=0.23.
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