Hydrogen Bromide → 6,8-Dibromoimidazo[1,2-a]pyrazine

HRID 1625488Notes

Reaction equation

HRID 1625488 reaction equation
CO[CH:3](OC)[CH2:4][Br:5].Br.O.[Br:10][C:11]1[C:12]([NH2:18])=[N:13][CH:14]=[C:15](Br)[N:16]=1>CN(C=O)C>[Br:5][C:4]1[N:16]=[C:11]([Br:10])[C:12]2[N:18]([CH:15]=[CH:14][N:13]=2)[CH:3]=1

Participants

6

Reactant 4

HCID 260Hydrogen BromideHCID 962WaterHCID 816722-Bromo-1,1-dimethoxyethaneHCID 6200042-Amino-3,5-dibromopyrazine

Product 1

HCID 150258436,8-Dibromoimidazo[1,2-a]pyrazineYield 82%

Reagents, catalysts & solvents 1

HCID 6228DimethylformamideSolvent

Procedure

A mixture of 5.0 g (30 mmol) of bromoacetaldehyde dimethyl acetal 1.0 ml of concentrated aqueous HBr solution and 4.0 ml of distilled water was brought to reflux for 1 h. After reaction, the mixture was alkalinized and extracted with ether. This organic phase was added to a solution of 1.0 g (4.0 mmol) of 3,5-dibromopyrazin-2-amine in 2 ml of DMF. The ether was removed and the mixture was stirred under a stream of nitrogen for 12 h. After reaction, the DMF was removed and the residue was dissolved in 5 ml of anhydrous ethanol and then it was brought to reflux for 1 h. The alcohol was then removed and the residue was dissolved in water, alkalinized with Na2CO3 and extracted with dichloromethane. After chromatography with alumina column (eluted with ether), 900 mg (yield: 82%) of 6,8-dibromoimidazo[1,2-a]pyrazine was obtained. ESI-MS (M+H+): 278.

Workup

  1. temperatureto reflux for 1 h
  2. customAfter reaction
  3. extractionextracted with ether
  4. customThe ether was removed
  5. customAfter reaction
  6. customthe DMF was removed
  7. dissolutionthe residue was dissolved in 5 ml of anhydrous ethanol
  8. temperatureto reflux for 1 h
  9. customThe alcohol was then removed
  10. dissolutionthe residue was dissolved in water
  11. extractionextracted with dichloromethane
  12. washAfter chromatography with alumina column (eluted with ether)

Sources & evidence

ORD record
ord-5b7be18ee64049b2bf6d247f9501ff61
Source dataset
uspto-grants-2014_07
Patent number
US08778977B2

Reaction notes

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