1-Butanol → 5-bromo-4-fluoro-2,3-dimethyl-2H-indazole

To a solution of 1-(3-bromo-2,6-difluorophenyl)ethanone (4.25 g) in n-butanol (50 ml) was added hydrazine monohydrate (1.06 ml) at room temperature, and the mixture was heated under reflux for 20 hr. The reaction mixture was cooled, and added to water, and the mixture was extracted with ethyl acetate. The obtained organic layer was washed with saturated aqueous sodium hydrogen carbonate solution and saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate). The residue was dissolved in ethyl acetate (50 ml), trimethyloxonium tetrafluoroborate (4.01 g) was added at room temperature, and the mixture was stirred at the same temperature for 3 hr. The reaction mixture was added dropwise to water, and the mixture was extracted with ethyl acetate. The organic layer was washed with water and saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate) to give the title compound (224 mg).

1. temperaturethe mixture was heated
2. temperatureunder reflux for 20 hr
3. temperatureThe reaction mixture was cooled
4. extractionthe mixture was extracted with ethyl acetate
5. washThe obtained organic layer was washed with saturated aqueous sodium hydrogen carbonate solution and saturated brine
6. dry with materialdried over anhydrous magnesium sulfate
7. concentrationconcentrated under reduced pressure
8. customThe residue was purified by silica gel column chromatography (hexane/ethyl acetate)
9. dissolutionThe residue was dissolved in ethyl acetate (50 ml)
10. additiontrimethyloxonium tetrafluoroborate (4.01 g) was added at room temperature
11. additionThe reaction mixture was added dropwise to water
12. extractionthe mixture was extracted with ethyl acetate
13. washThe organic layer was washed with water and saturated brine
14. dry with materialdried over anhydrous magnesium sulfate
15. concentrationconcentrated under reduced pressure
16. customThe residue was purified by silica gel column chromatography (hexane/ethyl acetate)

ORD record

ord-a5794697f9c74ed0a84667773c2f6c72

Source dataset

uspto-grants-2015_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09199963B2