[Cl:1][C:2]1[C:3]([F:13])=[C:4]([CH:8]=[C:9]([F:12])[C:10]=1[F:11])[C:5]([OH:7])=[O:6].[C:14](Cl)(=O)[C:15](Cl)=O.C(O)C>ClCCl.CN(C)C=O>[CH2:14]([O:6][C:5](=[O:7])[C:4]1[CH:8]=[C:9]([F:12])[C:10]([F:11])=[C:2]([Cl:1])[C:3]=1[F:13])[CH3:15]To a solution of 3-chloro-2,4,5-trifluorobenzoic acid (Example 20, 4.90 g, 23.3 mmol) in dichloromethane (50 mL) is added oxalyl chloride (5.1 mL, 58.2 mmol) and N,N-dimethylformamide (1 drop). After 45 minutes, the reaction mixture is concentrated under vacuum. The resulting residue is dissolved in dichloromethane (50 mL) and treated with ethanol (10 mL, 172 mmol). After 30 minutes, the reaction mixture is diluted with dichloromethane and washed with saturated NaHCO3, water, and brine. The organic layer is dried over MgSO4, filtered, and the filtrate is concentrated to afford the title compound (5.59 g). 1H NMR (CDCl3): δ 7.76–7.68 (m, 1H), 4.40 (q, 2H), 1.39 (t, 3H).
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