C[O:2][C:3](=[O:25])[C:4]1[CH:9]=[CH:8][C:7]([O:10][CH2:11][CH:12]2[CH2:16][C:15](=[O:17])[N:14]([C:18]3[CH:23]=[CH:22][C:21]([F:24])=[CH:20][CH:19]=3)[CH2:13]2)=[CH:6][CH:5]=1.CO.O.O[Li].O>C1COCC1>[F:24][C:21]1[CH:20]=[CH:19][C:18]([N:14]2[C:15](=[O:17])[CH2:16][CH:12]([CH2:11][O:10][C:7]3[CH:8]=[CH:9][C:4]([C:3]([OH:25])=[O:2])=[CH:5][CH:6]=3)[CH2:13]2)=[CH:23][CH:22]=1To a stirred solution of 4-[1-(4-fluorophenyl)-5-oxo-pyrrolidin-3-ylmethoxy]-benzoic acid methyl ester obtained in step 1 (0.14 g, 0.408 mmol) in THF:MeOH:H2O (6 mL, 2:1:3), LiOH.H2O was added at 20-25° C. The reaction mixture was stirred for 16 hours at that temperature. The solvents were removed under reduced pressure and the residue was diluted with water (10 ml). The aqueous layer was washed with DCM, acidified with 2% HCl. The acidified mixture was extracted with ethyl acetate, washed with brine, dried over Na2SO4. The organic layer was evaporated under reduced pressure to obtain 4-[1-(4-fluoro-phenyl)-5-oxo-pyrrolidin-3-ylmethoxy]-benzoic acid (0.130 g, quantitative) as a white solid.
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