Imidazole → 8-Hydroxy-6-methylimidazo[1,2-a]pyrazine

HRID 1809193Notes

Reaction equation

HRID 1809193 reaction equation
[Br-].C[N+:3]1[CH:4]=[CH:5][N:6]2[CH:11]=[C:10]([CH3:12])[NH:9][C:8](=[O:13])[C:7]=12.N1C=CN=C1>>[CH3:12][C:10]1[NH:9][C:8](=[O:13])[C:7]2[N:6]([CH:5]=[CH:4][N:3]=2)[CH:11]=1

Participants

3

Reactant 2

HCID 795ImidazoleHCID 866550891,6-Dimethyl-8-oxo-7,8-dihydro-imidazo[1,2-a]pyrazin-1-ium bromide salt

Product 1

HCID 457885228-Hydroxy-6-methylimidazo[1,2-a]pyrazineYield 39.7%

Conditions

Temperature
175 °C

Procedure

A mixture of 1,6-dimethyl-8-oxo-7,8-dihydro-imidazo[1,2-a]pyrazin-1-ium bromide salt (4.3 g, 16.4 mmol) and imidazole (20.4 g, 310 mmol) is stirred at 175° C. for 20 h. After this time the reaction mixture is cooled down to 100° C. and poured into ice-water with vigorous stirring. No precipitation is observed therefore the solvent is removed and the imidazole distilled off under vacuum at approx. 130° C. The solid remaining is triturated with DCM to give 6-methyl-7H-imidazo[1,2-a]pyrazin-8-one as a brown solid (970 mg). The mother liq. are purified by column chromatography using a gradient of (DMC/MeOH:99/1 to 95/5) to give a further 667 mg of 6-methyl-7H-imidazo[1,2-a]pyrazin-8-one as a pale yellow solid (1.66 g, 68%).

Workup

  1. temperatureAfter this time the reaction mixture is cooled down to 100° C.
  2. customNo precipitation
  3. customthe solvent is removed
  4. distillationthe imidazole distilled off under vacuum at approx. 130° C
  5. customThe solid remaining is triturated with DCM

Sources & evidence

ORD record
ord-2250f6869a814f4cb9ec6237b95b2f5c
Source dataset
uspto-grants-2013_01
Patent number
US08362018B2

Reaction notes

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