O-Phenylenediamine → 3,3-Dimethyl-1,2,3,4-tetrahydroquinoxalin-2-one

HRID 1736668Notes

Reaction equation

HRID 1736668 reaction equation
[C:1]1([NH2:8])[CH:6]=[CH:5][CH:4]=[CH:3][C:2]=1[NH2:7].Br[C:10]([CH3:17])([CH3:16])[C:11](OCC)=[O:12].C(NC(C)C)(C)C>CN(C=O)C>[CH3:16][C:10]1([CH3:17])[NH:8][C:1]2[C:2](=[CH:3][CH:4]=[CH:5][CH:6]=2)[NH:7][C:11]1=[O:12]

Participants

5

Reactant 3

HCID 7243O-PhenylenediamineHCID 7912DiisopropylamineHCID 11745Propanoic acid, 2-bromo-2-methyl-, ethyl ester2×

Product 1

HCID 5952033,3-Dimethyl-1,2,3,4-tetrahydroquinoxalin-2-one

Reagents, catalysts & solvents 1

HCID 6228DimethylformamideSolvent

Procedure

A mixture of 1,2-phenylenediamine (II, 7.55 g), ethyl 2-bromoisobutyrate (III, 12.8 ml), diisopropylamine (15.5 ml) and DMF (30 ml) is heated at 110° for 5 hr, after which an additional ethyl bromoisobutyrate (III, 0.5 ml) and diiopropylethylamine (0.8 ml) is added. After heating for 2 more hours, the reaction is cooled and the DMF is removed in under reduced pressure. The residue is stored overnight in the freezer and then partitioned between ethyl acetate, water, and saline. The phases are separated and the organic phase is dried over magnesium sulfate, the organic phase is removed under reduced pressure. The residue is chromatographed eluting with ethyl acetate/dichloromethane (20/80). The product crystallizes out in the column. The product is recrystallized from dichloromethane/hexane to give the title compound, mp 173°-174°; NMR (CDCl3) 1.41, 3.72, 6.67, 6.76, 6.87 and 8.50 δ.

Workup

  1. temperatureis heated at 110° for 5 hr
  2. temperatureAfter heating for 2 more hours
  3. temperaturethe reaction is cooled
  4. customthe DMF is removed in under reduced pressure
  5. custompartitioned between ethyl acetate, water, and saline
  6. customThe phases are separated
  7. dry with materialthe organic phase is dried over magnesium sulfate
  8. customthe organic phase is removed under reduced pressure
  9. customThe residue is chromatographed
  10. washeluting with ethyl acetate/dichloromethane (20/80)
  11. customThe product crystallizes out in the column
  12. customThe product is recrystallized from dichloromethane/hexane

Sources & evidence

ORD record
ord-9388969f65bc427e8065c85a59504c14
Source dataset
uspto-grants-1996_07
Patent number
US05541324

Reaction notes

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