C[O:2][C:3]([CH:5]1[CH2:9][C:8](=[O:10])[N:7]([C:11]2[CH:16]=[CH:15][C:14]([O:17][CH2:18][C:19]3[CH:24]=[CH:23][CH:22]=[C:21]([F:25])[CH:20]=3)=[CH:13][CH:12]=2)[CH2:6]1)=[O:4].[OH-].[Na+].Cl>C1COCC1>[F:25][C:21]1[CH:20]=[C:19]([CH:24]=[CH:23][CH:22]=1)[CH2:18][O:17][C:14]1[CH:13]=[CH:12][C:11]([N:7]2[C:8](=[O:10])[CH2:9][CH:5]([C:3]([OH:4])=[O:2])[CH2:6]2)=[CH:16][CH:15]=13.5 g (10.2 mmol) of [Rac] 1-[4-(3-fluoro-benzyloxy)-phenyl]-5-oxo-pyrrolidine-3-carboxylic acid methyl ester (Example 1d) are dispersed in 11.2 ml of a 1N solution of sodium hydroxide, and tetrahydrofuran is added to such an extent that a clear solution is obtained. Thereupon, the reaction mixture is heated to 50° C. during 1 h. For the working-up, the cooled solution is treated with 11.2 ml of 1N hydrochloric acid and THF evaporated under reduced pressure while the product starts to precipitate. The product is filtered and dried under vacuum to yield 2.39 g (71% of theory) of a white solid which is used in the next step without further purification.
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