1: (S)-4-(tert-butoxycarbonyl)morpholine-3-carboxylic acid With trifluoroacetic acid in dichloromethane T=0 - 20°C; 5 h; 2: (9H-Fluoren-9-yl)-methyl chloroformate With potassium carbonate in 1,4-dioxane; water T=0 - 20°C; 3 h;

1: 95 percent / hydrogen / Pt/C / methanol; CH2Cl2 / 16 h / 20 °C 2: 97 percent / aq. HCl / dioxane / 18 h / Heating View Scheme

1: 85 percent / p-toluenesulfonic acid monohydrate; molecular sieves 4 Angstroem / toluene / 1.75 h / Heating 2: 95 percent / hydrogen / Pt/C / methanol; CH2Cl2 / 16 h / 20 °C 3: 97 percent / aq. HCl / dioxane / 18 h / Heating View Scheme

sodium carbonate; N-ethyl-N,N-diisopropylamine in 1,4-dioxane; water T=20°C; Alkaline conditions;

potassium carbonate in 1,4-dioxane; water T=20°C; 3 h;

1: trifluoroacetic acid / dichloromethane / 5 h / 20 °C 2: potassium carbonate / 1,4-dioxane; water / 3 h / 20 °C View Scheme