Isoamyl Nitrite → 5-Bromo-7-(trifluoromethyl)-1H-indazole

To a solution of 4-bromo-2-methyl-6-(trifluoromethyl)aniline (3.3 g, 13 mmol) in toluene (65 mL) and glacial acetic acid (11.2 mL, 195 mmol) was added potassium acetate (10.2 g, 104 mmol) portionwise. After 15 minutes a large amount of precipitate had formed, hindering stirring of the reaction. The reaction was diluted with acetic acid (10 mL). Isoamyl nitrite (1.92 mL, 14.3 mmol) was then added dropwise and the reaction was stirred at room temperature for 3 hours. Additional isoamyl nitrite (0.5 mL, 3.7 mmol) was added and the reaction was left stirring for 15 hours. The reaction was diluted with water (100 mL) and stirred for 1.5 hours. The solution was partitioned between ethyl acetate and saturated aqueous sodium bicarbonate. The layers were separated and the organics were washed with brine, dried over magnesium sulfate, filtered, and concentrated. Purification by flash column chromatography (5-50% ethyl acetate/heptanes) gave the title compound (1.78 g, 52%) as a yellow powder. −ESI (M−H+1) 264.9; 1H NMR (400 MHz, CDCl3, δ): 8.13 (s, 1H), 8.09-8.11 (m, 1H), 7.76 (dd, J=1.66, 0.88 Hz, 1H).

1. customAfter 15 minutes a large amount of precipitate had formed
2. stirringthe reaction was stirred at room temperature for 3 hours
3. waitthe reaction was left
4. stirringstirring for 15 hours
5. stirringstirred for 1.5 hours
6. customThe solution was partitioned between ethyl acetate and saturated aqueous sodium bicarbonate
7. customThe layers were separated
8. washthe organics were washed with brine
9. dry with materialdried over magnesium sulfate
10. filtrationfiltered
11. concentrationconcentrated
12. customPurification by flash column chromatography (5-50% ethyl acetate/heptanes)

ORD record

ord-bc3de3d6614949a2b3dbc704057efed8

Source dataset

uspto-grants-2015_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09181252B2