Hydrochloric Acid → 5-phenyl-1H-thieno[3,2-c]pyrazole

Participants

Reaction Conditions

Reaction Steps

To a mixture of 1-(5-phenyl-thieno[3,2-c]pyrazol-1-yl)-ethanone [3.82 g, 15.8 mmol, Intermediate (44)] and ethanol (50 mL) was added 6 N hydrochloric acid (50.0 mL, 300 mmol) in one portion and the resulting mixture heated at 70° C. After 18 hours, the reaction was cooled to ambient temperature and neutralized with 25% aqueous potassium carbonate. The mixture was diluted with water (200 mL) and aged at 0° C. for 1 hour. The resulting solid was collected, washed three times with water (50 mL), and then dried under vacuum to give 5-phenyl-1H-thieno[3,2-c]pyrazole [2.93 g, 92%, Intermediate (45)] as a beige powder. LC/MS: 201.0 (M+H), RT=3.15 minutes).

Provenance & Evidence