[C]=O.[F:3][CH2:4][C:5]1([CH2:27][F:28])[CH:10]=[C:9](OS(C(F)(F)F)(=O)=O)[C:8]2[CH:19]=[C:20]([C:23]([F:26])([F:25])[F:24])[CH:21]=[CH:22][C:7]=2[O:6]1.[C:29]([O-:32])(=[O:31])C.[K+].[Cl-].[Li+].[OH-].[Na+].Cl>CN(C)C=O>[F:3][CH2:4][C:5]1([CH2:27][F:28])[CH:10]=[C:9]([C:29]([OH:32])=[O:31])[C:8]2[CH:19]=[C:20]([C:23]([F:24])([F:25])[F:26])[CH:21]=[CH:22][C:7]=2[O:6]1
A three-necked 200 -ml flask (equipped with a reflux condenser, a thermometer, and a CO introducing pipe connected with a balloon charged with carbon monoxide gas) was charged with 6.00 g (14.6 mmol) of trifluoromethanesulfonic acid 2,2-bis(fluoromethyl)-6-(trifluoromethyl)-2 H- 1 -benzopyran-4-yl ester, 5.7 g (58.2 mmol) of potassium acetate, 618 mg (14.6 mmol) of lithium chloride, and 75 ml of N,N-dimethylformamide. Under stirring of the mixture, 15 mg (0.0146 mmol) of tris(dibenzylidene) (chloroform) dipalladium (Pd2(dba)3(CHCl3)) were added. Under normal pressure, the reaction was conducted at 25° C. for 2 hr, while maintaining carbon monoxide atmosphere. After the reaction, the reaction liquid was poured into 150 ml of 2 mol/L sodium hydroxide aqueous solution, followed by shaking for 20 min, then adding concentrated hydrochloric acid to make it acid, and then extraction two times with 150 ml of MTBE. The resulting two MTBE extracts were combined together, followed by washing with water, then by drying with 15 g of magnesium sulfate anhydride, and then by filtration. Then, the MTBE was distilled off by an evaporator. The resulting residue was dissolved in 150 ml of a saturated sodium hydrogencarbonate aqueous solution, followed by washing with 15 ml of methylene chloride. The resulting aqueous layer was made acid by concentrated hydrochloric acid, followed by extraction two times with 150 ml of MTBE. The resulting two MTBE extracts were combined together, followed by washing with water, then by drying with 15 g of magnesium sulfate anhydride, and then by filtration. Then, the MTBE was distilled off with an evaporator, thereby obtaining 3.41 g (11.1 mmol) of 2,2-bis(fluoromethyl)- 6-(trifluoromethyl)-2 H- 1-benzopyran-4-carboxylic acid (yield: 76%).
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