Propylenediamine → 2-Methyl-5-phenylpyrazine

HRID 1054118Notes

Reaction equation

HRID 1054118 reaction equation
[CH2:1]([NH2:5])[CH:2]([NH2:4])[CH3:3].O.[C:7]1([C:13]([CH:15]=O)=O)[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1.[OH-].[K+]>C(O)C>[CH3:3][C:2]1[CH:1]=[N:5][C:13]([C:7]2[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=2)=[CH:15][N:4]=1

Participants

5

Reactant 3

HCID 6567PropylenediamineHCID 14797Potassium HydroxideHCID 12215922Glyoxal, phenyl-, hydrate

Product 1

HCID 125659662-Methyl-5-phenylpyrazine

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

To a stirred solution of propylenediamine (2.94 g, 0.04 mol) in ethanol was added phenylglyoxal-monohydrate (5.00 g, 0.03 mol) at 0° C. within 30 minutes. After stirring for 1.5 hours at room temperature KOH (2.10 g, 0.04 mol) was added and the reaction mixture was refluxed for 12 hours. Then the solvent was removed under vacuum and the residue was extracted with ether. The organic phases were washed with brine and dried over MgSO4. Crude product was purified by flash chromatography on silica-gel using a mixture of hexane/ethyl acetate (7:3→3:7) as eluent. After flash chromatography the product was recrystallized from hexane. White solid. Yield: 780 mg, 15%. 1H NMR (CDCl3, 500 MHz): δH (ppm)=2.57 (s, 3H), 7.38-7.50 (m, 3H), 7.91-7.99 (m, 2H), 8.43-8.49 (m, 1H), 8.87 (d, J=1.5 Hz, 1H); 13C NMR (CDCl3, 125 MHz): δC (ppm)=21.2, 126.6, 128.9, 129.4, 136.5, 140.9, 143.8, 149.8, 151.9; (ESI): m/z=170.94 [M+H]+.

Workup

  1. additionwas added
  2. temperaturethe reaction mixture was refluxed for 12 hours
  3. customThen the solvent was removed under vacuum
  4. extractionthe residue was extracted with ether
  5. washThe organic phases were washed with brine
  6. dry with materialdried over MgSO4
  7. customCrude product was purified by flash chromatography on silica-gel
  8. additiona mixture of hexane/ethyl acetate (7:3→3:7) as eluent
  9. customAfter flash chromatography the product was recrystallized from hexane

Sources & evidence

ORD record
ord-227c63c06e25462aaee384e10721fe4c
Source dataset
uspto-grants-2016_07
Patent number
US09394290B2

Reaction notes

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