1: methyl (3R)-3-amino-4-(2,4,5-trifluorophenyl)butanoate With water; lithium hydroxide hydrate in tetrahydrofuran T=0 - 30°C; 2: di-tert-butyl dicarbonate in tetrahydrofuran; water T=25 - 30°C; 6 h; 3: With sodium hydrogen sulphate in water pH=2;

1: 93 percent / CH2Cl2 / 3 h / 20 °C 2: 99 percent / aq. LiOH / tetrahydrofuran; methanol / 3 h / 20 °C View Scheme

1.1: water; lithium hydroxide hydrate / tetrahydrofuran / 0 - 30 °C 2.1: water; tetrahydrofuran / 6 h / 25 - 30 °C 2.2: pH 2 3.1: N-ethyl-N,N-diisopropylamine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; benzotriazol-1-ol / N,N-dimethyl-formamide / 13 h / 0 - 30 °C 4.1: hydrogenchloride / methanol / 12 h / 25 - 45 °C View Scheme