[CH3:1][O:2][C:3](=[O:21])[C:4]1[CH:19]=[CH:18][C:7]([C:8]([O:10]CC2C=CC=CC=2)=[O:9])=[CH:6][C:5]=1[F:20]>CCO.CCOC(C)=O.[Pd]>[CH3:1][O:2][C:3](=[O:21])[C:4]1[CH:19]=[CH:18][C:7]([C:8]([OH:10])=[O:9])=[CH:6][C:5]=1[F:20]A solution of the crude 2-fluoroterephthalic acid 4-benzyl ester 1-methyl ester (8, 0.14 mol) in EtOH (210 mL) and EtOAc (210 mL) is treated with 10% Pd/C (4.0 g) under hydrogen atmosphere at room temperature for 5 h. After filtration of the catalyst, the filtrate is evaporated in vacuo. Crystals are collected and washed with ether/hexane (1:1) to give 2-fluoroterephthalic acid 1-methyl ester (9) as white solid.
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