Hydrochloric Acid → Zaleplon

Participants

Reaction Steps

N-[3-[3-(dimethylamino)-1-oxo-2-propenyl]phenyl]-N-ethylacetamide (26.0 g, 0.1 mol) and 3-amino-4-cyanopyrazole (10.8 g, 0.1 mol) were dissolved in the mixture of water (350 cm3) and methanol (200 cm3). Concentrated (37%) hydrochloric acid (12.5 cm3, 0.12 mol) was then added and the mixture was stirred at room temperature for about 2 hours. The reaction mixture was then cooled to about 5° C. and the crystalline product formed was collected, washed with water and dried at about 60° C. to yield zaleplon (29.8 g, 97.7%) in 99.08% purity as determined by HPLC.

Provenance & Evidence