1: ethyl (S)-3-butanoylamino-3-(4-cyanophenyl)propanoate With hydrogenchloride 3 h; Heating; 2: di-tert-butyl dicarbonate With potassium carbonate in 1,4-dioxane; water T=20°C; 5 h;

hydrogenchloride 3 h; Heating; Title compound not separated from byproducts;