1.1: 4-(N,N-dimethlyamino)pyridine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; N-ethyl-N,N-diisopropylamine / dichloromethane / 3 h / 20 °C 2.1: N,O-bis(trimethylsilyl) trifluoroacetamide / acetonitrile / 0.5 h / 20 °C / Inert atmosphere 2.2: 20 °C / Inert atmosphere View Scheme