Acetyl chloride (2.9 g) was dissolved in 50 ml of dry dichloromethane, mixed with 5.3 ml of triethylamine, and after addition of N,N-diethyl-N′-[(R)-1-(4-nitrophenyl)pyrrolidin-3-yl]-ethane-1,2-diamine (5.8 g), stirred at room temperature for 30 minutes. Subsequently, (LCMS check), water (10 ml) was added to the reaction, and the mixture was extracted with dichloromethane (2×10 ml). The combined organic phases were dried over magnesium sulfate, the solvent was removed, and the crude product was separated by chromatography on silica gel (dichloromethane/methanol 10:1). This resulted in the product with the molecular weight of 348.45 (C18H28N4O3); MS (ESI): 349 (M+H+).
