Hydrochloric Acid → 2,2-bis(fluoromethyl)-6-trifluoromethyl-2H-1-benzopyran-4-carboxylic acid

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Reaction Conditions

Reaction Steps

A mixture of 4-bromo-2,2-bis(fluoromethyl)-6-trifluoromethyl-2H-1-benzopyran (1.72 g), potassium acetate (2.00 g), potassium iodide (0.85 g), triphenylphosphine (27 mg), palladium acetate (11 mg) and N,N-dimethylacetamide (10 ml) was stirred under a CO atmosphere at 120° C. for 9 hours. To the reaction mixture, 2 N HCl was added and the precipitating crystals were recovered by filtration. To the recovered crystals, ethyl acetate was added and the insoluble matter was filtered off; the filtrate was washed with a saturated aqueous solution of sodium thiosulfate and a saturated aqueous solution of sodium chloride, dried with anhydrous sodium sulfate and concentrated under reduced pressure; the resulting residue was dissolved in a saturated aqueous solution of sodium hydrogencarbonate washed with dichloromethane; concentrated HCl was added to the resulting aqueous layer to make it acidic and the precipitating crystals were recovered by filtration. The recovered crystals were dissolved in ethyl acetate, dried with anhydrous magnesium sulfate and concentrated under reduced pressure; the resulting residue was recrystallized with a solvent consisting of a mixture of ethyl acetate and hexane, thereby giving 2,2-bis(fluoromethyl)-6-trifluoromethyl-2H-1-benzopyran-4-carboxylic acid (1.25 g) represented by the formula (C2-1) and having a melting point of 162-163° C.

Provenance & Evidence