tert-Butyl carbazate → 1h-Indazole-5-carboxylic acid,1-acetyl-3-(4-fluorophenyl)-

Participants

Reaction Steps

To a solution containing tert-butyl carbazate (0.79 g, 0.006 mol) in pyridine (30 mL) was added 1-acetyl-3-(4-fluorophenyl)-1H-indazole-5-carbonyl chloride (1.7 g, 0.005 mol). The reaction mixture was allowed to stir at ambient temperature for 18 hours. Solvent was removed and water was added to the mixture. The reaction was extracted with ethyl acetate. Some 1-acetyl-3-(4-fluorophenyl)-1H-indazole-5-carboxylic acid was isolated. The reaction mixture was treated with an equivalent of tert-butyl carbazate and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride in dichloromethane and allowed to stir overnight. The reaction was extracted with ethyl acetate. The product was taken up in a solution of 0.3% ammonia in methanol (˜50 mL) and allowed to stir overnight. The reaction mixture was extracted with dichloromethane, dried with magnesium sulfate, and concentrated. The material was purified by silica gel chromatography using 2% methanol in dichloromethane. The product was taken up in ethanol and gaseous hydrochloric acid was bubbled into solution. A solid precipitated out and was collected by filtration. This material was dried to provide the title compound (0.91 g, 56% yield). ES-MS (m/z) 271 [M+1]+.

Provenance & Evidence