Hydrogen Bromide → 6-Bromo-1H-indazole

HRID 844242Notes

Reaction equation

HRID 844242 reaction equation
N([O-])=O.[Na+].N[C:6]1[CH:14]=[C:13]2[C:9]([CH:10]=[N:11][NH:12]2)=[CH:8][CH:7]=1.[OH-].[Na+].[BrH:17]>O.[Cu]>[Br:17][C:6]1[CH:14]=[C:13]2[C:9]([CH:10]=[N:11][NH:12]2)=[CH:8][CH:7]=1

Participants

7

Reactant 4

HCID 260Hydrogen BromideHCID 14798Sodium HydroxideHCID 814231H-Indazol-6-amineHCID 23668193Sodium Nitrite

Product 1

HCID 178424716-Bromo-1H-indazoleYield 16%

Reagents, catalysts & solvents 2

HCID 23978CopperCatalystHCID 962WaterSolvent

Conditions

Temperature
90 °C

Procedure

Sodium nitrite (315 mg, 4.56 mmol) was added in 2 portions to an ice-cooled suspension of 6-aminoindazole (500 mg, 3.8 mmol) in water (0.4 mL) and hydrobromic acid (48%, 1.8 mL). The reaction mixture was stirred for 10 minutes longer than required for the brown gas to disappear. Copper powder (35 mg, 0.55 mmol) was then added and the mixture heated gently until nitrogen evolution began. The reaction mixture was then alternately heated and cooled to control the rate of reaction. When nitrogen evolution ceased, the reaction mixture was heated at 90° C. for 30 minutes, cooled to room temperature, neutralized with aqueous sodium hydroxide and the product extracted into ethyl acetate. The organic layer was washed sequentially with water and brine, dried over sodium sulfate and the solvent removed in vacuo. Flash chromatography on silica gel (20-40% ethyl acetate in hexane) yield the title product (119 mg, 16%).

Workup

  1. temperaturecooled
  2. temperaturethe mixture heated gently until nitrogen evolution
  3. temperatureThe reaction mixture was then alternately heated
  4. temperaturecooled
  5. customthe rate of reaction
  6. temperaturecooled to room temperature
  7. extractionthe product extracted into ethyl acetate
  8. washThe organic layer was washed sequentially with water and brine
  9. dry with materialdried over sodium sulfate
  10. customthe solvent removed in vacuo

Sources & evidence

ORD record
ord-732ed1f74097457bb1863f04188543ef
Source dataset
uspto-grants-2002_04
Patent number
US06380242B1

Reaction notes

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