CC(C)([O-])C.[K+].[F:7][C:8]1[CH:15]=[CH:14][C:11]([CH:12]=O)=[CH:10][CH:9]=1.[C:16]([O:24]C)(=[O:23])[CH2:17][CH2:18][C:19]([O:21][CH3:22])=[O:20]>C(O)(C)(C)C>[CH3:22][O:21][C:19](=[O:20])[C:18](=[CH:12][C:11]1[CH:14]=[CH:15][C:8]([F:7])=[CH:9][CH:10]=1)[CH2:17][C:16]([OH:24])=[O:23]To a refluxing mixture of potassium tert-butoxide (27 g, 242 mmol) and tert-butanol (150 mL) was added a solution of 4-fluoro-benzaldehyde (20 g, 161 mmol) and dimethyl succinate (28 g, 193.2 mmol) in tert-butanol (100 mL) dropwise. After being heated at reflux for 3 hours, the mixture was concentrated in vacuo to remove tert-butanol. The residue was dissolved in 1 N hydrochloric acid (180 mL). The resulting aqueous solution was extracted with ethyl acetate (100 mL×3). The combined organic layers were dried over sodium sulfate, and concentrated in vacuo. The residue was purified by column chromatography (elution with 30% ethyl acetate in petroleum ether) to afford 2-(4-fluoro-benzylidene)-succinic acid 1-methyl ester (25.5 g, 66%) as a light yellow solid. 1H NMR (400 MHz, CD3OD) δ ppm 7.84 (s, 1H), 7.41-7.46 (m, 2H), 7.13-7.20 (m, 2H), 3.81 (s, 3H), 3.49 (s, 2H).
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