4-(N,N-dimethlyamino)pyridine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride in dichloromethane T=20°C; Cooling with ice;

1: 2,2-Dimethyl-[1,3]dioxane-4,6-dione With triethylamine in dichloromethane T=0 - 5°C; 2: C8H4ClF3O in dichloromethane T=0 - 5°C; 3 h;

1.1: ethanol / 3 h / 70 °C 2.1: formic acid / ethanol / 3 h / Reflux 2.2: 2 h / 40 °C / Reflux 3.1: methanol / Reflux 4.1: sodium carbonate / water; methanol / 3 h / 30 °C / pH 10 5.1: sodium hydroxide; water / methanol / 2 h / 40 - 45 °C 5.2: pH 3 / Acidic conditions View Scheme

1.1: ethanol / 3 h / 70 °C 2.1: formic acid / ethanol / 3 h / Reflux 2.2: 2 h / 40 °C / Reflux 3.1: methanol / Reflux 4.1: sodium carbonate / water; methanol / 3 h / 30 °C / pH 10 5.1: sodium hydroxide; water / methanol / 2 h / 40 - 45 °C 5.2: pH 3 / Acidic conditions 6.1: hydrogenchloride; water / ethyl acetate / 4 h / 20 °C View Scheme