Ethyl Acetate → 6-Bromo-3,4-dihydro-4-methyl-2(1H)-quinoxalinone

HRID 2230048Notes

Reaction equation

HRID 2230048 reaction equation
[Br:1][C:2]1[CH:3]=[CH:4][C:5]([N+:14]([O-])=O)=[C:6]([N:8]([CH2:10][C:11](O)=[O:12])[CH3:9])[CH:7]=1.O.O.[Sn](Cl)Cl.[OH-].[Na+].CCOC(C)=O>C(O)C.O.Cl>[Br:1][C:2]1[CH:7]=[C:6]2[C:5](=[CH:4][CH:3]=1)[NH:14][C:11](=[O:12])[CH2:10][N:8]2[CH3:9]

Participants

8

Reactant 4

HCID 8857Ethyl AcetateHCID 14798Sodium HydroxideHCID 61436Stannous chloride dihydrateHCID 226677282-[(5-Bromo-2-nitrophenyl)(methyl)amino]acetic acid

Product 1

HCID 226677406-Bromo-3,4-dihydro-4-methyl-2(1H)-quinoxalinoneYield 36.1%

Reagents, catalysts & solvents 3

HCID 313Hydrochloric AcidSolventHCID 702EthanolSolventHCID 962WaterSolvent2×

Procedure

A solution of [(5-bromo-2-nitro-phenyl)-methyl-amino]-acetic acid (8 g, 27.6 mmol) and tin(II) chloride dihydrate (20 g, 88 mmol) in ethanol (200 Ml), water (30 ml) and concentrated HCl (10 ml) was heated to reflux for 6 hours. After cooling to room temperature the mixture was diluted with water and was adjusted to pH 9 with 2N aqueous sodium hydroxide solution. After addition of EtOAc, the precipitated tin hydroxide was filtered off. The layers were separated and the organic layer was washed with water, then brine, dried (MgSO4) and evaporated. The residue was recrystallized from ethanol to afford 6-bromo-4-methyl-3,4-dihydro-1H-quinoxalin-2-one (2.4 g, 36%), which was used without further purification. 1H-NMR (DMSO-d6) δ 2.78 (s, 3H), 3.89 (s, 2H), 6.81 (d, 1H, J=1.76 Hz), 6.95 (dd, 1H, J=8.49, 1.81 Hz), 7.05 (d, 1H, J=8.47 Hz), 10.63 (s, 1H).

Workup

  1. temperatureto reflux for 6 hours
  2. filtrationthe precipitated tin hydroxide was filtered off
  3. customThe layers were separated
  4. washthe organic layer was washed with water
  5. dry with materialbrine, dried (MgSO4)
  6. customevaporated
  7. customThe residue was recrystallized from ethanol

Sources & evidence

ORD record
ord-a83b70089e814272a2b2521469cc1f75
Source dataset
uspto-grants-2002_07
Patent number
US06423699B1

Reaction notes

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