Hydrazine → 5-bromo-1H-indazole

To 5-bromo-2-fluorobenzaldehyde 161 (2.0 g, 9.85 mmol.) was added hydrazine (10 mL). The reaction mixture was heated under gentle reflux for 4 hours. Excess hydrazine was evaporated under reduced pressure. Ethyl acetate (200 mL) was added. The organic layer was washed with water and brine. The organic layer was dried over sodium sulfate. The organic solvent was evaporated under reduced pressure. The crude product was purified by flash column chromatography to yield the desired 5-bromoindazole 162 (1.04 g, 5.28 mmol.).

1. temperatureThe reaction mixture was heated
2. temperatureunder gentle reflux for 4 hours
3. customExcess hydrazine was evaporated under reduced pressure
4. additionEthyl acetate (200 mL) was added
5. washThe organic layer was washed with water and brine
6. dry with materialThe organic layer was dried over sodium sulfate
7. customThe organic solvent was evaporated under reduced pressure
8. customThe crude product was purified by flash column chromatography

ORD record

ord-00060140c3f54f07abda747d0d594f71

Source dataset

uspto-grants-2009_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07528132B2