Lithium hydroxide, monohydrate → (R)-3-(tert-butoxycarbonylamino)-4-(2,4,5-trifluorophenyl)butanoic acid

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Reaction Steps

To a solution of (R)-Methyl-3-[N-(tert-butoxycarbonyl)amino]-4-(2,4,5-tri-fluorophenyl)butanoate of Example 4 (1.28 g, 3.69 mmol) in 15 mL THF and 15 mL water was added 3 equiv. LiOH.H2O. The reaction mixture was stirred for 16 h. 10 ml saturated NaHCO3 was added. THF was evaporated and the aq solution was acidified to pH 2-3 with NaHSO4, then extracted by ethyl acetate (3×15 mL). The combined organic phase was washed with brine and dried over Na2SO4. Concentration in vacuo afforded 1.17 g of white solid (95.1%). 1H NMR (300 MHz, CD3OD) 7.13-7.03 (m, 2H), 4.20-4.10 (m, 1H), 3.00-2.90 (m, 1H), 2.75-2.60 (m, 1H), 2.45-2.55 (m, 2H), 1.35 (s, 9H)

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