Benzo(B)Thiophene → 3-(5,6-Dimethoxybenzo[b]thien-2-yl)-3-oxo-propanoic acid methyl ester

HRID 1709970Notes

Reaction equation

HRID 1709970 reaction equation
[H-].[Na+].[C:3](=[O:8])([O:6][CH3:7])OC.[C:9]([C:12]1[S:16][C:15]2[CH:17]=[C:18]([O:23][CH3:24])[C:19]([O:21][CH3:22])=[CH:20][C:14]=2[CH:13]=1)(=[O:11])[CH3:10].S1C2C=CC=CC=2C=C1.[H-].[K+]>O1CCCC1.C(O)(=O)C>[CH3:7][O:6][C:3](=[O:8])[CH2:10][C:9]([C:12]1[S:16][C:15]2[CH:17]=[C:18]([O:23][CH3:24])[C:19]([O:21][CH3:22])=[CH:20][C:14]=2[CH:13]=1)=[O:11]

Participants

8

Reactant 5

HCID 7221Benzo(B)ThiopheneHCID 12021Dimethyl CarbonateHCID 24758Sodium hydrideHCID 82127Potassium hydrideHCID 230352502-Acetyl-5,6-dimethoxy-benzo[b]thiophene

Product 1

HCID 540542623-(5,6-Dimethoxybenzo[b]thien-2-yl)-3-oxo-propanoic acid methyl ester

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolventHCID 8028TetrahydrofuranSolvent2×

Procedure

A mixture of sodium hydride (60% dispersion in oil, 10.9 g) and dimethyl carbonate (18.7 ml) in dry tetrahydrofuran (210 ml) was stirred and heated at reflux under an atmosphere of nitrogen. A solution of 2-acetyl-5,6-dimethoxy-benzo[b]thiophene (21.0 g) in dry tetrahydrofuran (315 ml) was added dropwise over 30 min. Shortly after the addition of the benzothiophene solution had commenced potassium hydride (22.7% dispersion in oil) was added to initiate the reaction (sufficient to cause a permanent pink colour). When the evolution of gas had ceased (90 min.) the reaction mixture was cooled in an ice bath and treated with glacial acetic acid (34 ml). The resultant yellow solution was poured into ice-cold water (2 liter), stirred, and the yellow solid was filtered, washed with n-hexane and dried at 50° C. under vacuum to give 3-(5,6-dimethoxybenzo[b]thien-2-yl)-3-oxo-propanoic acid methyl ester (22.0 g). A portion crystallized from dichloromethane/diethyl ether had m.p. 129°-130° C.

Workup

  1. temperatureheated
  2. temperatureat reflux under an atmosphere of nitrogen
  3. additionwas added
  4. customthe reaction (sufficient
  5. custom(90 min.)
  6. temperaturewas cooled in an ice bath
  7. stirringstirred
  8. filtrationthe yellow solid was filtered
  9. washwashed with n-hexane
  10. customdried at 50° C. under vacuum

Sources & evidence

ORD record
ord-c827f4d26d2b4429b74e7c675b94648f
Source dataset
uspto-grants-1990_08
Patent number
US04952571

Reaction notes

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