[CH3:1][O:2][C:3](=[O:23])[C:4]1[CH:9]=[C:8]([C:10]([O:12]CC)=[CH2:11])[C:7]([C:15]([F:18])([F:17])[F:16])=[CH:6][C:5]=1[NH:19][C:20](=[O:22])[CH3:21].Cl.CCOC(C)=O>C1COCC1>[CH3:1][O:2][C:3](=[O:23])[C:4]1[CH:9]=[C:8]([C:10](=[O:12])[CH3:11])[C:7]([C:15]([F:18])([F:17])[F:16])=[CH:6][C:5]=1[NH:19][C:20](=[O:22])[CH3:21]A solution of crude 2-acetylamino-5-(1-ethoxy-vinyl)-4-trifluoromethyl-benzoic acid methyl ester from above in THF (100 mL) was treated with aqueous hydrochloric acid (1N, 50 mL), and the mixture was stirred at r.t. for 1 h under nitrogen. The mixture was then poured into EtOAc and washed once with water. The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. The crude product was purified by column chromatography (silica gel 60, hexanes/EtOAc 2:1) to give 5-acetyl-2-acetylamino-4-trifluoromethyl-benzoic acid methyl ester (10.7 g, 35.1 mmol, 76% over two steps) as a white powder, m.p. 66-69° C., ESI-MS: m/z 326 [M+Na]+.
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