Hydrazine → 6-Bromo-1H-indazole

HRID 1850038Notes

Reaction equation

HRID 1850038 reaction equation
F[C:2]1[CH:9]=[C:8]([Br:10])[CH:7]=[CH:6][C:3]=1[CH:4]=O.[NH2:11][NH2:12]>C(COC)OC>[Br:10][C:8]1[CH:9]=[C:2]2[C:3]([CH:4]=[N:11][NH:12]2)=[CH:6][CH:7]=1

Participants

4

Reactant 2

HCID 9321HydrazineHCID 1435174-Bromo-2-fluorobenzaldehyde

Product 1

HCID 178424716-Bromo-1H-indazoleYield 85.5%

Reagents, catalysts & solvents 1

HCID 80711,2-DimethoxyethaneSolvent

Procedure

A solution of 2-fluoro-4-bromobenzaldehyde (5.09 g, 25 mmol) was dissolved in glyme (25 mL) and slowly treated over 10 minutes with anhydrous hydrazine (25 mL, 0.8 mol, 32 eq.). The resulting biphasic mixture was then held at reflux overnight. The reflux condenser was replaced with a short-path distillation head and about half the solvent distilled, at which time the reaction flask showed one phase and two phases were evident in the distillate. The undistilled residue was cooled and treated with water (25 mL), forming a white precipitate. This solid was collected by filtration, washed thoroughly with water, and dried in vacuo to give 6-bromoindazole (4.21 g, 85%) as white crystals.

Workup

  1. temperatureat reflux overnight
  2. distillationdistilled, at which time the reaction flask
  3. temperatureThe undistilled residue was cooled
  4. additiontreated with water (25 mL)
  5. customforming a white precipitate
  6. filtrationThis solid was collected by filtration
  7. washwashed thoroughly with water
  8. customdried in vacuo

Sources & evidence

ORD record
ord-f089a3b2c4384aa99f96dd2222aa0c2f
Source dataset
uspto-grants-2015_02
Patent number
US08957049B2

Reaction notes

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