1-Benzothiophene-2-carbaldehyde → (E)-3-(benzo[b]thienyl)-2-propenoic acid ethyl ester

HRID 653955Notes

Reaction equation

HRID 653955 reaction equation
[S:1]1[C:5]([CH:6]=O)=[CH:4][C:3]2[CH:8]=[CH:9][CH:10]=[CH:11][C:2]1=2.[CH3:12][CH2:13][O-:14].[Na+].[CH3:16][CH2:17][OH:18]>CCO>[CH2:13]([O:14][C:17](=[O:18])/[CH:16]=[CH:6]/[C:5]1[S:1][C:2]2[CH:11]=[CH:10][CH:9]=[CH:8][C:3]=2[CH:4]=1)[CH3:12]

Participants

4

Reactant 2

HCID 7365001-Benzothiophene-2-carbaldehydeHCID 23706232Ethanol sodium ethoxide

Product 1

HCID 10633343(E)-3-(benzo[b]thienyl)-2-propenoic acid ethyl esterYield 113.5%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

To a solution of benzo[b]thiophene-2-carboxaldehyde (4.40 g, 27.1 mmol) and triethyl phosphonoacetate (16.6 mL, 83.2 mmol) in absolute EtOH (120 mL) was added a solution of EtONa/EtOH (made from 1.92 g of Na and 70 mL of EtOH) at 40° C. with stirring. The mixture was then heated at reflux for 40 min. After cooling to r.t. the mixture was concentrated to remove most of the solvent, mixed with crushed ice (60 mL) and water (60 mL), and was extracted with Et2O (3×450 mL). The combined extracts were washed with brine (2×200 mL), dried (MgSO4), and evaporated to dryness. The crude solid was purified by a flash chromatography on silica gel using 15% EtOAc/hexane as the eluent to give-(E)-3-(benzo[b]thien-2-yl)-2-propenoic acid ethyl ester (4.44 g, 19.1 mmol) in 71% yield as an amorphous solid.

Workup

  1. temperatureThe mixture was then heated
  2. temperatureat reflux for 40 min
  3. concentrationwas concentrated
  4. customto remove most of the solvent
  5. additionmixed with crushed ice (60 mL) and water (60 mL)
  6. extractionwas extracted with Et2O (3×450 mL)
  7. washThe combined extracts were washed with brine (2×200 mL)
  8. dry with materialdried (MgSO4)
  9. customevaporated to dryness
  10. customThe crude solid was purified by a flash chromatography on silica gel using 15% EtOAc/hexane as the eluent

Sources & evidence

ORD record
ord-e80da495aa6a41b7a365d920b43f39f8
Source dataset
uspto-grants-1992_07
Patent number
US05128448

Reaction notes

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