1: (2S)-2-amino-3,3-dimethylbutanoic acid With sodium hydroxide in water pH=11.5; 2: 1,1-dimethylethyl isocyanate in water pH=9.3; Cooling with ice;

1: With 1,1'-carbonyldiimidazole in tetrahydrofuran; dichloromethane T=25 - 30°C; 13.5 h; 2: With hydrogenchloride in tetrahydrofuran; dichloromethane; water pH=2.5; 0.25 h;

1: in dichloromethane T=20 - 30°C; 14 - 16.5 h; Heating / reflux; 2: With hydrogenchloride; water in dichloromethane T=15 - 20°C; pH=1.0 - 2.0; 0.333333 - 1 h; Product distribution / selectivity;

1.1: N-ethyl-N,N-diisopropylamine; benzotriazol-1-ol / dichloromethane / 0.17 h / 0 - 5 °C 1.2: 6 h / 25 - 30 °C 2.1: water; lithium hydroxide hydrate / tetrahydrofuran / 6 h / 25 - 30 °C 3.1: N-ethyl-N,N-diisopropylamine; benzotriazol-1-ol; dicyclohexyl-carbodiimide / dichloromethane / 5 h / 0 - 30 °C 4.1: Dess-Martin periodane / dichloromethane / 0 - 30 °C View Scheme

1: N-ethyl-N,N-diisopropylamine; HATU / acetonitrile / 5 h / 25 - 30 °C 2: Dess-Martin periodane / dichloromethane / 0 - 30 °C View Scheme

2,6-dimethylpyridine; benzotriazol-1-ol; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride in acetonitrile T=10 - 30°C; 3 - 5 h;