4-(2-Amino-ethyl)-piperazin-2-one (5.51 g) and triethylamine (9.07 mL, 6.59 g) were added to 1,4-dioxane (100 mL), N,N-dimethylacetamide (20 mL), and water (10 mL) and mixed until dissolved. 4-Chloro-3-nitrobenzenesulfonamide (7.00 g) was added, and the mixture was heated to 90° C. for 16 hours. The mixture was cooled and the solvent was removed under vacuum. The crude material was purified by recrystallization from 20% methanol in dichloromethane with subsequent washing of the recrystallized solid with 10% methanol in dichloromethane followed by washing with 100% dichloromethane.
