Lithium Hydroxide → 3-(4-((3-(4-Ethylphenyl)-5-(trifluoromethyl)isothiazol-4-yl)methoxy)-3-fluorophenyl)-2-methylpropanoic acid

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Reaction Steps

Into a 50-mL round-bottom flask, was placed ethyl 3-(4-[[3-(4-ethylphenyl)-5-(trifluoromethyl)-1,2-thiazol-4-yl]methoxy]-3-fluorophenyl)-2-methylpropanoate (74 mg, 0.15 mmol, 1.00 equiv) (prepared according to the procedure of Example 1 step 5 by coupling (3-(4-ethylphenyl)-5-(trifluoromethyl)isothiazol-4-yl)methanol and ethyl 3-(3-fluoro-4-hydroxy phenyl)-2-methylpropanoate), tetrahydrofuran (1.5 mL). This was followed by the addition of a solution of LiOH (74 mg, 3.09 mmol, 20.69 equiv) in water (1.5 mL) dropwise with stirring. The resulting solution was stirred overnight at 25° C. The reaction progress was monitored by LCMS. The resulting mixture was concentrated under vacuum. Hydrogen chloride (2N) was employed to adjust the pH to 1. The solids were collected by filtration. The crude product (35 mg) was purified by Prep-HPLC with the following conditions (1# water 2767-16): Column, SunFire Prep C18 Sum, 19*150 nm; mobile phase, water with 0.05% trifluoroacetic acid and CH3CN. (70% CH3CN up to 90% in 7.0 min, up to 100% in 2.0 min, down to 70% in 2.0 min); Detector, 254 nm. This resulted in 3.4 mg (5%) of 3-(4-((3-(4-ethylphenyl)-5-(trifluoro methyl)isothiazol-4-yl)methoxy)-3-fluorophenyl)-2-methylpropanoic acid as a white solid. 1H NMR (300 Hz, CD3OD): 7.64 (d, J=8.4 Hz, 2H), 7.32 (d, J=8.1 Hz, 2H), 6.92-7.03 (m, 3H), 5.14 (s, 2H), 2.89-2.97 (m, 1H), 2.62-2.75 (m, 4H), 1.27 (t, J=7.8 Hz, 3H), 1.16 (d, J=3.3 Hz, 3H). 19F NMR (300 Hz, CD3OD): δ−56.57, −76.95, −135.59. Mass spectrum (ESI, m/z): Calcd. for C24H21.5F5.5NO4S, 468.1 (M-0.5CF3COOH+H). found 468.1.

Provenance & Evidence