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

1: 2-(tert-butoxycarbonyloxyimino)-2-phenylacetonitrile; S-(-)-piperazine-2-carboxylic acid dihydrochloride With sodium hydroxide in 1,4-dioxane; water T=20°C; pH=11; 2: N-(benzyloxycarbonyloxy)-succinimide in 1,4-dioxane; water T=0 - 20°C; pH=10; 3: With hydrogenchloride in diethyl ether; water pH=1;

1: 40percent NaOH / dioxane; H2O / 2.5 h 2: 40percent NaOH / dioxane; H2O / 14 h View Scheme

methanol in toluene T=20°C;

potassium carbonate in N,N-dimethyl-formamide T=20°C; 2 h;

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

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