2-Butanone, 3-bromo- → N-(4,5-dimethyl-1H-imidazol-2-yl)acetamide

Participants

Reaction Steps

A dry round bottom flask was charged with a 0.3 M (20.0 mmol) solution of 3-bromobutan-2-one. Acetylguanidine (60.0 mmol) in dry DMF was added to the mixture. The mixture was stirred at room temperature for 96 hours. The solvent was evaporated off and the residue was washed with water, filtered, dried and recrystallized with methanol to give crude N-(4,5-dimethyl-1H-imidazol-2-yl)acetamide. This material was suspended in 100 mL of 1:1 MeOH:H2O solution with 1.5 mL of H2SO4, and heated to reflux for 16 hours (overnight). The reaction mixture was then allowed to cool to room temperature and concentrated at reduced pressure. The resulting crude material was treated with ethanol and ether, treated in an ultrasonic bath and concentrated at reduced pressure. The crude product was further purified by silica column chromatography (starting with 5% MeOH in dichloromethane, in increments of 5% to 35% MeOH in dichloromethane) to give 609 mg of 4,5-dimethyl-1H-imidazol-2-amine.

Provenance & Evidence