(S)-ethyl 1-((S)-2-hydroxy-2-(4-(5-(3-phenyl-4-(trifluoromethyl)isoxazol-5-yl)-1,2,4-oxadiazol-3-yl)phenyl)ethyl)piperidine-3-carboxylate → (S)-1-((S)-2-hydroxy-2-(4-(5-(3-phenyl-4-(trifluoromethyl)isoxazol-5-yl)-1,2,4-oxadiazol-3-yl)phenyl)ethyl)piperidine-3-carboxylic acid

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Reaction Steps

(S)-Ethyl 1-((S)-2-hydroxy-2-(4-(5-(3-phenyl-4-(trifluoromethyl)isoxazol-5-yl)-1,2,4-oxadiazol-3-yl)phenyl)ethyl)piperidine-3-carboxylate (89 mg, 0.16 mmol) was heated at 50° C. in 6N HCl (5 mL) in acetonitrile (5 mL). The reaction mixture was stirred overnight and then filtered and purified by HPLC. HPLC conditions: PHENOMENEX® Luna C18 5 micron column (250×30mm); 25-100% CH3CN/water (0.1% TFA); 25 minute gradient; 30 mL/min. Isolated fractions with correct mass were freeze-dried overnight to yield 36 mg of (S)-1-((S)-2-hydroxy-2-(4-(5-(3-phenyl-4-(trifluoromethyl)isoxazol-5-yl)-1,2,4-oxadiazol-3-yl)phenyl)ethyl) piperidine-3-carboxylic acid as a TFA salt. 1H NMR (400 MHz, MeOH-d3) δ ppm 8.23 (2H, d, J=8.35 Hz), 7.65-7.74 (4H, m), 7.54-7.65 (3H, m), 5.29 (1H, t, J=7.03 Hz), 4.00 (1H, br. s.), 3.43-3.75 (1H, m), 3.34-3.41 (2H, m), 2.82-3.24 (2H, m), 2.26 (1H, d, J=11.86 Hz), 1.84-2.14 (2H, m), 1.52-1.75 (1H, m). MS (m+1)=529. HPLC Peak RT=3.24 minutes. Purity=98%.

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