Diethyl Oxalate → 5-Methoxy-2-thiopheneglyoxylic acid ethyl ester

HRID 2419209Notes

Reaction equation

HRID 2419209 reaction equation
[CH3:1][O:2][C:3]1[S:4][CH:5]=[CH:6][CH:7]=1.C([Li])CCC.S1C=CC=C1[Li].[C:19](OCC)(=[O:25])[C:20]([O:22][CH2:23][CH3:24])=[O:21].[NH4+].[Cl-]>C1COCC1.CCCCCC>[CH2:23]([O:22][C:20](=[O:21])[C:19]([C:5]1[S:4][C:3]([O:2][CH3:1])=[CH:7][CH:6]=1)=[O:25])[CH3:24]

Participants

8

Reactant 5

HCID 7268Diethyl OxalateHCID 25517Ammonium ChlorideHCID 856102-MethoxythiopheneHCID 178418339ButyllithiumHCID 178418439HCID 178418439, compound

Product 1

HCID 544362655-Methoxy-2-thiopheneglyoxylic acid ethyl ester

Reagents, catalysts & solvents 2

HCID 8028TetrahydrofuranSolvent2×HCID 8058HexaneSolvent

Procedure

2-Methoxythiophene (15.4 g) is dissolved in 100 ml anhydrous THF and butyl lithium (0.135 moles) in hexane is added dropwise. The solution is stirred at room temperature 15 hr and then heated at reflux for 1 hr. After cooling, the clear solution is transferred to a dropping funnel by means of a siphon. The solution of thienyl lithium is added dropwise to a solution of diethyl oxalate (19.7 g) in 150 ml THF at -78° C. After stirring 2 hr at -78° C, the mixture is brought to -10° C and treated with saturated NH4Cl solution. The aqueous fraction is separated and extracted several times with ether. The combined ether extracts are washed with water and brine, dried (MgSO4) and concentrated. Chromatography on silica gel (eluant = benzene) gives 5-methoxy-2-thiopheneglyoxylic acid ethyl ester (2; X1 = CH3O, X2 and X3 = H and R10 = C2H5); mp 136° - 137° C after recrystallization from benzene-hexane.

Workup

  1. temperatureheated
  2. temperatureat reflux for 1 hr
  3. temperatureAfter cooling
  4. customthe clear solution is transferred to a dropping funnel by means of a siphon
  5. stirringAfter stirring 2 hr at -78° C
  6. customis brought to -10° C
  7. customThe aqueous fraction is separated
  8. extractionextracted several times with ether
  9. washThe combined ether extracts are washed with water and brine
  10. dry with materialdried (MgSO4)
  11. concentrationconcentrated

Sources & evidence

ORD record
ord-ddb5baae49264a27bbbb9a6f2fb09b20
Source dataset
uspto-grants-1978_08
Patent number
US04105663

Reaction notes

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