反应详情

To a stirred suspension of N,N′-dimethylurea (commercial) (72.1 g, 819 mmol) and DMAP (commercial) (100 g, 819 mmol) in pyridine (300 mL) under N2 was added dropwise with stirring acetic anhydride (255 mL, 2701 mmol). On complete addition the reaction mixture was allowed to stir at RT for 3 hours. After this time, the volatiles were removed under reduced pressure to afford a viscous orange pyridine solution, which was seeded with product. The mixture was stored at 0-4° C. for 7 days. The resulting crystalline solid was filtered under reduced pressure, washed with diethyl ether and dried to afford the title compound as colourless crystals. The mother liquors were further purified by chromatography on silica eluting with 30-50% EtOAc in iso-hexane. The resulting solid was diluted with diethyl ether (500 mL) and was stored at 0-4° C. overnight. The resulting crystals were filtered off and washed with iso-hexane, then dried to afford the title compound as colourless crystals and combined. The title product was obtained as white crystals.

1. additionOn complete addition the reaction mixture
2. customAfter this time, the volatiles were removed under reduced pressure
3. customto afford a viscous orange pyridine solution, which
4. waitThe mixture was stored at 0-4° C. for 7 days
5. filtrationThe resulting crystalline solid was filtered under reduced pressure
6. washwashed with diethyl ether
7. customdried