Sulfuric Acid → Ethyl 5,6,7,8-tetrahydroquinoxaline-2-carboxylate

HRID 385522Notes

Reaction equation

HRID 385522 reaction equation
[C:1]([O:6][CH2:7][CH3:8])(=[O:5])[C:2]([O-])=O.[N:9]1[C:18]2[CH2:17][CH2:16][CH2:15][CH2:14][C:13]=2[N:12]=C[CH:10]=1.S(=O)(=O)(O)O.S(OOS([O-])(=O)=O)([O-])(=O)=O.[Na+].[Na+].C(=O)([O-])O.[Na+]>ClCCl.O.[N+]([O-])([O-])=O.[Ag+].C(Cl)(Cl)Cl>[N:12]1[C:13]2[CH2:14][CH2:15][CH2:16][CH2:17][C:18]=2[N:9]=[CH:10][C:2]=1[C:1]([O:6][CH2:7][CH3:8])=[O:5]

Participants

10

Reactant 5

HCID 1118Sulfuric AcidHCID 368225,6,7,8-TetrahydroquinoxalineHCID 62655Sodium Persulfate2×HCID 516892Sodium BicarbonateHCID 21943339Ethanedioic acid, monoethyl ester

Product 1

HCID 57815216Ethyl 5,6,7,8-tetrahydroquinoxaline-2-carboxylateYield 22.1%

Reagents, catalysts & solvents 4

HCID 24470Silver NitrateCatalyst2×HCID 962WaterSolventHCID 6212ChloroformSolventHCID 6344DichloromethaneSolvent

Procedure

To a solution of 1.0 g of monoethyl oxalate in 14 mL of dichloromethane, 0.47 g of 5,6,7,8-tetrahydroquinoxaline, 91 μL of concentrated sulfuric acid, 1.7 g of sodium persulfate, and a suspension of 60 mg of silver nitrate in 14 mL of water were added, and the mixture was heated under reflux while stirring for 1 hour 30 minutes. To the reaction mixture, 1.7 g of sodium persulfate and 60 mg of silver nitrate were further added, and the mixture was heated under reflux for 1 hour 50 minutes. The reaction mixture was charged with chloroform and adjusted to pH 7.5 with a saturated aqueous sodium hydrogen carbonate solution, the insoluble substance was filtered off, and the organic layer was separated. The organic layer was washed with a saturated aqueous sodium chloride solution, and dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. The resultant residue was purified by flash silica gel column chromatography using gradient elution with hexane:ethyl acetate=90:10 to 67:33 to obtain 0.16 g of ethyl 5,6,7,8-tetrahydroquinoxaline-2-carboxylate as a yellow oily substance.

Workup

  1. additionwere added
  2. temperaturethe mixture was heated
  3. temperatureunder reflux
  4. temperaturethe mixture was heated
  5. temperatureunder reflux for 1 hour 50 minutes
  6. filtrationthe insoluble substance was filtered off
  7. customthe organic layer was separated
  8. washThe organic layer was washed with a saturated aqueous sodium chloride solution
  9. dry with materialdried over anhydrous magnesium sulfate
  10. distillationthe solvent was distilled off under reduced pressure
  11. customThe resultant residue was purified by flash silica gel column chromatography
  12. washelution with hexane

Sources & evidence

ORD record
ord-e1a8ee3a9e094d2c8fa46585a9fb96d4
Source dataset
uspto-grants-2013_02
Patent number
US08367831B2

Reaction notes

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