Sodium Hydroxide → (R)-3-(tert-butoxycarbonylamino)-4-(2,4,5-trifluorophenyl)butanoic acid

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Reaction Conditions

Reaction Steps

Refer to the common known method Tetrahedron Asymmetry, 2006, 17(2), 205-209. 3-tert-Butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyric acid ethyl ester 1e (10 g, 27.7 mmol) and sodium hydroxide (3.32 g, 83.1 mmol) were dissolved in 150 mL of the mixture of methanol and water (v:v=1:1). The reaction mixture was stirred at 40-45° C. for 1-1.5 hours, then part of the solution was evaporated under reduced pressure. The residues were added with a little of water, then the pH was adjusted to 2-3 with 1 M hydrochloric acid in an ice-water bath. The mixture was extracted with ethyl acetate (200 mL×3), and the combined organic phase was washed with 200 mL of saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure, and then the residues were recrystallized from ethyl acetate/n-hexane to obtain the title compound (R)-3-tert-butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyric acid 1f (9.2 g) as a white solid, which was directly used in the next step. MS m/z (ESI): 332.3 [M−1].

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