1: 4-(benzyloxy-carbonyl)-2-piperazinecarboxylic acid With sodium hydrogencarbonate in 1,4-dioxane; water T=20°C; 0.5 h; 2: di-tert-butyl dicarbonate in 1,4-dioxane; water T=0 - 20°C;

1: 2-(S)-piperazine carboxylic acid; N-(benzyloxycarbonyloxy)-succinimide With sodium hydroxide in 1,4-dioxane; water T=20°C; pH=9.5 - 11; 0.75 h; 2: 2-(tert-butoxycarbonyloxyimino)-2-phenylacetonitrile in 1,4-dioxane; water T=20°C; pH=9.5; 17 h; 3: With hydrogenchloride in 1,4-dioxane; water pH=2;

sodium hydroxide in methanol

methanol; sodium hydroxide in tetrahydrofuran

potassium carbonate in N,N-dimethyl-formamide T=0 - 20°C; 2 h;