Potassium Iodide → 6-iodo-1H-indazole

Participants

Reaction Steps

Sodium nitrite (5.87 g, 85 mmol) in water (20 mL) was added dropwise to an ice-cooled solution of 6-aminoindazole (10 g, 75.6 mmol) in DMF (80 mL) and hydrochloric acid (6M, 40 mL). The mixture was stirred for 30 minutes. Potassium iodide (13.5 g) was then added in small portions (gas evolution occurred) and the mixture stirred for 1 h before warming to room temperature for 16 h. The reaction was neutralized with aqueous sodium bisulfite, followed by aqueous sodium hydroxide. The mixture was filtered to remove solids, and the solid was washed with water to remove impurities, and then with ethyl acetate and THF to collect the product. The organic washes were evaporated and recombined with the aqueous layer for extraction with ethyl acetate (3×250 mL). The organic layer was washed sequentially with water and brine, dried over sodium sulfate, and the solvent removed in vacuo. Filtration chromatography on silica gel (35-60% ethyl acetate in hexane) gave a yellow solid which was triturated firstly with 50% ethyl acetate in hexane and then with ethyl acetate to yield the product (4.96 g).

Provenance & Evidence