in dichloromethane T=0 - 20°C; 1.5 h; Inert atmosphere;

1: monobromoacetic acid With 1-hydroxy-pyrrolidine-2,5-dione; dicyclohexyl-carbodiimide in 1,4-dioxane T=20°C; 2 h; 2: N-butylamine in 1,4-dioxane T=20°C; 5 h;