1: (DL)-norvaline With sodium hydroxide in 1,4-dioxane; water 6 h; 2: di-tert-butyl dicarbonate in 1,4-dioxane; water T=20°C; Cooling with ice;

Bacillus licheniformis in water T=30°C; pH=7.5; 15 h;

dipyridinium dichromate in N,N-dimethyl-formamide T=25°C; 6 h;

1: 90 percent / pyridine 2: dimethylformamide / 1 h / 0 °C 3: 92 percent / NaBH4 / methanol / 1 h / 25 °C 4: 93 percent / mCPBA / CH2Cl2 / 1 h / 25 °C 5: 95 percent / PyH*OTs / CH2Cl2 / 24 h / 25 °C 6: 95 percent / 1.) n-BuLi / 1.) THF, -78 deg C; 2.) -50 deg C, 2 h 7: PyH*OTs / ethanol / 6 h / 60 °C 8: 6 percent Na-Hg, Na2HPO4 / methanol / 24 h / 25 °C 9: pyridinium dichromate / dimethylformamide / 6 h / 25 °C View Scheme

1: dimethylformamide / 1 h / 0 °C 2: 92 percent / NaBH4 / methanol / 1 h / 25 °C 3: 93 percent / mCPBA / CH2Cl2 / 1 h / 25 °C 4: 95 percent / PyH*OTs / CH2Cl2 / 24 h / 25 °C 5: 95 percent / 1.) n-BuLi / 1.) THF, -78 deg C; 2.) -50 deg C, 2 h 6: PyH*OTs / ethanol / 6 h / 60 °C 7: 6 percent Na-Hg, Na2HPO4 / methanol / 24 h / 25 °C 8: pyridinium dichromate / dimethylformamide / 6 h / 25 °C View Scheme

1: 95 percent / 1.) n-BuLi / 1.) THF, -78 deg C; 2.) -50 deg C, 2 h 2: PyH*OTs / ethanol / 6 h / 60 °C 3: 6 percent Na-Hg, Na2HPO4 / methanol / 24 h / 25 °C 4: pyridinium dichromate / dimethylformamide / 6 h / 25 °C View Scheme

1: 6 percent Na-Hg, Na2HPO4 / methanol / 24 h / 25 °C 2: pyridinium dichromate / dimethylformamide / 6 h / 25 °C View Scheme

1: PyH*OTs / ethanol / 6 h / 60 °C 2: 6 percent Na-Hg, Na2HPO4 / methanol / 24 h / 25 °C 3: pyridinium dichromate / dimethylformamide / 6 h / 25 °C View Scheme

triethylamine in 1,4-dioxane; water 4 h; Ambient temperature;

1: 82 percent / CDI, DIEA / tetrahydrofuran; dimethylformamide / Ambient temperature 2: 90 percent / LiAlH4 / diethyl ether / 0.5 h / 0 - 5 °C 3: 1.) aq. NaHSO3 / 1.) MeOH, 5 deg C, overnight, 2.) MeOH, H2O, AcOEt, RT, 5 h 4: conc. aq. HCl, anisole / dioxane / Heating 5: 1 N NaOH / dioxane / 4 h / Ambient temperature View Scheme