Tetrafluoroboric acid → 4-bromo-1H-indazole

3-bromo-2-methylaniline (1.70 ml, 13.8 mmol) was added to water (6 ml) in a corning, conical reaction vessel cooled in an ice water bath, and HBF4 (6.5 ml, 49.7 mmol) was added. Then, NaNO2 (0.99 g, 14.3 mmol) in water (2 ml), cooled in an ice water bath, was added via syringe, and the thick suspension was stirred while being warmed to room temperature over 45 minutes. It was then recooled in an ice water bath and filtered via a Buchner funnel. The solid was washed with 5% aqueous HBF4 (100 ml), the filtrate was filtered again, and the solid from both filtrations was washed with precooled (0 C) MeOH (4×25 ml) and precooled (0 C) diethyl ether (2×25 ml). The solid was then dried on a Buchner funnel for 30 minutes and then added to a flask containing KOAc (2.90 g, 29.5 mmol) and 18-c-6 (203 mg, 0.768 mmol) suspended in chloroform (100 ml). The reaction was stirred at room temperature for 2 hours and 20 minutes and then filtered, and the solid was washed with chloroform. The filtrate was washed with water (50 ml) and brine (50 ml), dried over sodium sulfate, filtered, concentrated, and diluted with water (150 ml). The suspension was filtered, and the solid was washed with hexanes, collected, and put under vacuum overnight to give title compound (773.6 mg, 28%). MS (ESI pos. ion) m/z: 197 (M+H). Calc'd Exact Mass for C7H5BrN2: 196.

1. temperaturecooled in an ice water bath
2. additionwas added via syringe
3. customIt was then recooled in an ice water bath
4. filtrationfiltered via a Buchner funnel
5. washThe solid was washed with 5% aqueous HBF4 (100 ml)
6. filtrationthe filtrate was filtered again
7. filtrationthe solid from both filtrations
8. washwas washed with precooled (0 C) MeOH (4×25 ml)
9. customThe solid was then dried on a Buchner funnel for 30 minutes
10. additionadded to a flask
11. stirringThe reaction was stirred at room temperature for 2 hours and 20 minutes
12. filtrationfiltered
13. washthe solid was washed with chloroform
14. washThe filtrate was washed with water (50 ml) and brine (50 ml)
15. dry with materialdried over sodium sulfate
16. filtrationfiltered
17. concentrationconcentrated
18. additiondiluted with water (150 ml)
19. filtrationThe suspension was filtered
20. washthe solid was washed with hexanes
21. customcollected
22. customput under vacuum overnight

ORD record

ord-0d0694816ccc4cceaae9233915779cc3

Source dataset

uspto-grants-2011_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08017601B2