Sulfuric Acid → Ethyl (e)-5-(bromo-2-thienyl)-4-hexenoate

HRID 49318

Reaction equation

HRID 49318 reaction equation
[Br-:1].[C:2]([CH2:5][CH2:6][CH2:7][P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)([OH:4])=[O:3].C[C:28]([CH3:31])([O-])C.[K+].Br[C:34]1[S:38][C:37]([C:39](=O)[CH3:40])=[CH:36][CH:35]=1.S(=O)(=O)(O)O>C1COCC1.C(O)C>[Br:1][C:36]1[CH:35]=[CH:34][S:38][C:37]=1/[C:39](/[CH3:40])=[CH:7]/[CH2:6][CH2:5][C:2]([O:4][CH2:28][CH3:31])=[O:3]

Participants

7

Reactant 4

HCID 1118Sulfuric AcidHCID 793352-Acetyl-5-bromothiopheneHCID 10717451(3-Carboxypropyl)(triphenyl)phosphanium bromideHCID 23665647Potassium tert-butoxide

Product 1

HCID 131724373Ethyl (e)-5-(bromo-2-thienyl)-4-hexenoate

Reagents, catalysts & solvents 2

HCID 702EthanolSolventHCID 8028TetrahydrofuranSolvent3×

Conditions

Temperature
130 °C

Procedure

22.2 g (51.7 mmol) of (3-carboxypropyl)triphenylphosphonium bromide are dried under vacuum for 1 h with heating at 130° C., and then cooled to room temperature and dissolved in 200 mL of anhydrous THF. 11.5 g (102.5 mmol) of potassium tert-butoxide in 100 mL of THF are then added slowly, after which the orange-red mixture is stirred for 15 minutes. A solution of 7 g (34 mmol) of 1-(5-bromo-2-thienyl)ethanone in 100 mL of THF is then added dropwise and the reaction medium is stirred for 15 hours. After treatment with saturated ammonium chloride solution, extraction with ethyl acetate, drying and evaporation of the solvents from the organic phase, the residue obtained is purified by chromatography on a column of silica. An ochre-coloured solid is obtained (m.p.: 62-64° C., m=5.8 g; Y=62%). This product is then dissolved in 100 mL of ethanol and 2 mL of sulphuric acid are then added. The reaction medium is brought to reflux and stirred for 2 hours. After treatment with water, the medium is extracted with ethyl acetate and the organic phases are then combined, dried and concentrated under reduced pressure. The residue obtained is purified by chromatography on a column of silica (eluent: 95 heptane/5 ethyl acetate) to give the pure trans isomer in the form of a yellow oil (m=3.4 g; Y=77%).

Workup

  1. temperaturecooled to room temperature
  2. stirringthe reaction medium is stirred for 15 hours
  3. extractionAfter treatment with saturated ammonium chloride solution, extraction with ethyl acetate
  4. customdrying
  5. customevaporation of the solvents from the organic phase
  6. customthe residue obtained
  7. customis purified by chromatography on a column of silica
  8. customAn ochre-coloured solid is obtained (m.p.: 62-64° C., m=5.8 g; Y=62%)
  9. temperatureto reflux
  10. stirringstirred for 2 hours
  11. extractionAfter treatment with water, the medium is extracted with ethyl acetate
  12. customdried
  13. concentrationconcentrated under reduced pressure
  14. customThe residue obtained
  15. customis purified by chromatography on a column of silica (eluent: 95 heptane/5 ethyl acetate)
  16. customto give the pure trans isomer in the form of a yellow oil (m=3.4 g; Y=77%)

Sources & evidence

ORD record
ord-ee00e825bdce420eb62a46cb8465a609
Source dataset
uspto-grants-2004_03
Patent number
US06706725B1

Linked notes

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