Hydrogen Bromide → Imidazo(1,2-a)pyrazine

HRID 1086167Notes

Reaction equation

HRID 1086167 reaction equation
CO[CH:3](OC)[CH2:4]Br.Br.O.[NH2:10][C:11]1[CH:16]=[N:15][CH:14]=[CH:13][N:12]=1>CN(C)C=O>[N:12]1[CH:13]=[CH:14][N:10]2[CH:4]=[CH:3][N:15]=[CH:16][C:11]=12

Participants

6

Reactant 4

HCID 260Hydrogen BromideHCID 962WaterHCID 78747AminopyrazineHCID 816722-Bromo-1,1-dimethoxyethane

Product 1

HCID 2771670Imidazo(1,2-a)pyrazine

Reagents, catalysts & solvents 1

HCID 6228DimethylformamideSolvent

Procedure

A mixture of 34 g (0.2 mol) of bromoacetaldehyde dimethyl acetal, 6,6 ml of concentrated aqueous HBr solution and 28 ml of distilled water is brought to reflux for one hour. After reaction, the mixture is alkalinized and extracted with ether. This organic phase is added to a solution of 19 g (0.2 mol) of aminopyrazine in 50 ml of dimethylformamide (DMF). The ether is removed by distillation and the mixture is maintained with stirring and under a stream of nitrogen for 12 hours. After reaction, the DMF is distilled off; the reaction medium is dissolved in 150 ml of anhydrous ethanol, and then brought to reflux for one hour. The alcohol is then removed by distillation; the residue is dissolved in water, alkalinized with Na2CO3 and extracted using dichloromethane. After chromatography on a neutral alumina column (eluant =anhydrous ether), 10.7 g (Yld=45%) of imidazo[1,2-a]pyrazine (m.p. 84° C.). are obtained.

Workup

  1. temperatureto reflux for one hour
  2. customAfter reaction
  3. extractionextracted with ether
  4. customThe ether is removed by distillation
  5. temperaturethe mixture is maintained
  6. customAfter reaction
  7. distillationthe DMF is distilled off
  8. dissolutionthe reaction medium is dissolved in 150 ml of anhydrous ethanol
  9. temperatureto reflux for one hour
  10. customThe alcohol is then removed by distillation
  11. dissolutionthe residue is dissolved in water
  12. extractionextracted
  13. customare obtained

Sources & evidence

ORD record
ord-d7886ca493d44b7da1def83ab42a8680
Source dataset
uspto-grants-1991_07
Patent number
US05028605

Reaction notes

Loading…