sodium hydroxide in 1,4-dioxane; water T=20°C; pH=11;

sodium hydroxide in 1,4-dioxane; water 2.5 h;

1: S-(-)-piperazine-2-carboxylic acid dihydrochloride With sodium hydroxide in 1,4-dioxane; water T=0°C; 2: di-tert-butyl dicarbonate in 1,4-dioxane; water T=20°C; 5 h;

in 1,4-dioxane; water pH=11;

sodium carbonate in 1,4-dioxane; water T=0 - 20°C; 16 h;

1: With borane-THF in tetrahydrofuran T=90°C; 4 h; Heating / reflux; 2: With methanol in tetrahydrofuran T=0°C;

1.1: sodium hydrogencarbonate / water; 1,4-dioxane / 16 h / 20 °C 2.1: potassium carbonate / N,N-dimethyl-formamide / 0.08 h / 20 °C 2.2: 2 h / 20 °C View Scheme

1: 40percent NaOH / dioxane; H2O / 14 h 2: 85 percent / 1-ethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, HOBt, Et3N / dimethylformamide / 18 h 3: 96 percent / H2 / 10percent Pd/C / methanol / 3 h 4: 83 percent / (i-Pr)2NEt / propan-2-ol / 3.5 h 5: aq. LiOH / 1,2-dimethoxy-ethane / 0.5 h 6: imidazole / 1,2-dimethoxy-ethane / 20 h / 0 - 20 °C 7: 92 percent / 1-ethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, HOBt, Et3N / dimethylformamide / 18 h / 0 - 20 °C 8: 69 percent / 8N HCl / propan-2-ol / 6 h / Ambient temperature View Scheme

1: 40percent NaOH / dioxane; H2O / 14 h 2: 85 percent / 1-ethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, HOBt, Et3N / dimethylformamide / 18 h 3: 96 percent / H2 / 10percent Pd/C / methanol / 3 h 4: 83 percent / (i-Pr)2NEt / propan-2-ol / 3.5 h 5: aq. LiOH / 1,2-dimethoxy-ethane / 0.5 h 6: imidazole / 1,2-dimethoxy-ethane / 20 h / 0 - 20 °C 7: 92 percent / 1-ethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, HOBt, Et3N / dimethylformamide / 18 h / 0 - 20 °C 8: 69 percent / 8N HCl / propan-2-ol / 6 h / Ambient temperature 9: 76 percent / Et3N / dimethylformamide / 12 h View Scheme

sodium hydrogencarbonate in 1,4-dioxane; water T=20°C; 16 h;