Sulfuric Acid → 6-(trifluoromethyl)-1H-indazol-5-amine

Participants

Reaction Steps

Under ice-cooling, 1.01 g (12.0 mmol) of sodium nitrate was added to a mixture of 1.54 g (8.29 mmol) of 6-trifluoromethylindazole and 5 ml of concentrated sulfuric acid, and the mixture was stirred for 1 hour. The reaction mixture was poured onto ice and after ammonia water was added dropwise to the mixture under ice-cooling until pH reached 10 or higher, the precipitated solid was collected by filtration and then washed with water, followed by drying. The resulting crude product was dissolved in 50 ml of methanol, activated carbon was added to the mixture, and the mixture was filtered. 0.20 g of 5% Palladium-on-carbon was added to the filtrate, and the mixture was stirred under a hydrogen atmosphere at room temperature for 14 hours. The mixture was filtered through Celite and the filtrate was concentrated under reduced pressure to give 1.57 g (yield: 94%, two steps) of 5-amino-6-trifluoromethylindazole.

Provenance & Evidence