Trifluoroacetic acid → 4-[5-(3,5-Dichloro-phenyl)-4-hydroxy-5-trifluoromethyl-4,5-dihydro-isoxazol-3-yl]-2-methyl-benzoic acid

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Reaction Steps

To a solution of 4-[5-(3,5-dichloro-phenyl)-4-hydroxy-5-trifluoromethyl-4,5-dihydro-isoxazol-3-yl]-2-methyl-benzoic acid tert-butyl ester (Example 12.1) (500 mg) in dichloromethane (20 ml) was added trifluoroacetic acid (“TFA”) (4 ml) and the reaction mixture was stirred at ambient temperature for 16 hours. To the reaction mixture was diluted with water and the phases were separated. The organic layer was washed with water and brine, dried over magnesium sulfate and concentrated. The residue was suspended in diisopropyl ether/pentane (1:3). The solids were isolated by filtration and washed with pentane to give 4-[5-(3,5-dichloro-phenyl)-4-hydroxy-5-trifluoromethyl-4,5-dihydro-isoxazol-3-yl]-2-methyl-benzoic acid (395 mg) as a white solid. M.p. 215-217° C. 1H-NMR (CDCl3, 400 MHz): 7.98 (d, 1H), 7.72 (s, 1H), 7.69 (s, 1H), 7.52 (s, 2H), 7.40 (s, 1H), 5.76 (s, 1H), 2.61 (s, 3H).

Provenance & Evidence