[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([OH:8])=[C:4]([C:9]([F:12])([F:11])[F:10])[CH:3]=1.[OH-:13].[Na+].Cl>C(Cl)(Cl)Cl.CC(C)=O>[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([O:8][C:4]([CH3:9])([CH3:3])[C:5]([OH:8])=[O:13])=[C:4]([C:9]([F:10])([F:11])[F:12])[CH:3]=1A three-neck round bottom flask affixed with an overhead stirrer was charged with 4-chloro-2-(trifluoromethyl)phenol (prepared according methods described in U.S. Pat. No. 4,262,152), (5.0 g, 127 mmol, 1.0 eq) and dissolved in chloroform (3.3 mL) and acetone (8.4 mL). NaOH pellets (4.2 g, 104 mmol, 3.75 eq) were added in 2 portions and the mixture was stirred vigorously for 40 min. The resulting slurry was acidified to pH 2 with 3N HCl and extracted with EtOAc. The organic extracts were treated with satd. aq. sodium bicarbonate, and the basic layer was acidified to pH 4 with conc. HCl and extracted with EtOAc. The organic layer was washed with brine, dried over sodium sulfate and concentrated to afford 2.7 g (37%) of 2-(4-chloro-2-(trifluoromethyl)phenoxy)-2-methylpropanoic acid as a light brown crystalline solid. 1H NMR (400 MHz, CDCl3): δ 7.57 (d, J=2.6 Hz, 1H), 7.40 (dd, J=8.9, 2.6 Hz, 1H), 6.91 (d, J=8.9 Hz, 1H), 1.67 (s, 6H). LCMS (0-99% MeCN/water, 5 min, negative ion), Tret=2.99 min, [M−H]−=281.3 observed.
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