Iodine → 1-(Benzo[b]thiophen-4-yl)propan-1-one

HRID 2183610Notes

Reaction equation

HRID 2183610 reaction equation
Br[C:2]1[C:10]2[CH:9]=[CH:8][S:7][C:6]=2[CH:5]=[CH:4][CH:3]=1.[Mg].II.CON(C)[C:17](=[O:20])[CH2:18][CH3:19]>O1CCCC1>[S:7]1[CH:8]=[CH:9][C:10]2[C:2]([C:17](=[O:20])[CH2:18][CH3:19])=[CH:3][CH:4]=[CH:5][C:6]1=2

Participants

6

Reactant 4

HCID 807IodineHCID 5462224MagnesiumHCID 11344007N-Methoxy-N-methylpropionamideHCID 120942084-Bromobenzo[b]thiophene2×

Product 1

HCID 224739661-(Benzo[b]thiophen-4-yl)propan-1-oneYield 64.5%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Procedure

Approximately 5 ml of a solution of 4-bromobenzo[b]thiophene (9.55 g) in tetrahydrofuran (100 ml) was added under nitrogen to magnesium turnings (1.5 g). Two crystals of iodine were added and heat was applied to initiate the reaction. The remainder of the 4-bromobenzo[b]thiophene solution was added at reflux temperature over 20 minutes, then the mixture was heated under reflux for 15 minutes. A solution of N-methoxy-N-methylpropionamide (6.0 g) in tetrahydrofuran (50 ml) was added, the mixture was heated under reflux for 40 minutes, then it was allowed to cool to ambient temperature and quenched by the addition of 2M hydrochloric acid (125 ml). The mixture was stirred at ambient temperature for 1 hour, then the product was extracted into ethyl acetate (300 ml). The extract was washed with water (3×200 ml) and saturated aqueous sodium chloride solution (200 ml), dried (Na2SO4), and the solvents were removed in vacuo. The residue was purified by flash chromatography over silica using petroleum ether (b.p. 60-80° C.) followed by a 97:3 mixture of petroleum ether (b.p. 60-80° C.) and ethyl acetate as eluant. Appropriate fractions were combined and the solvents removed in vacuo to give 1-(benzo[b]thiophen-4-yl)propan-1-one (5.5 g) as a colourless oil which was used without further purification.

Workup

  1. temperatureheat
  2. customthe reaction
  3. temperatureat reflux temperature over 20 minutes
  4. temperaturethe mixture was heated
  5. temperatureunder reflux for 15 minutes
  6. temperaturethe mixture was heated
  7. temperatureunder reflux for 40 minutes
  8. customquenched by the addition of 2M hydrochloric acid (125 ml)
  9. extractionthe product was extracted into ethyl acetate (300 ml)
  10. washThe extract was washed with water (3×200 ml) and saturated aqueous sodium chloride solution (200 ml)
  11. dry with materialdried (Na2SO4)
  12. customthe solvents were removed in vacuo
  13. customThe residue was purified by flash chromatography over silica
  14. additionfollowed by a 97:3 mixture of petroleum ether (b.p. 60-80° C.) and ethyl acetate as eluant
  15. customthe solvents removed in vacuo

Sources & evidence

ORD record
ord-b3cc5a099f6f4e1eaa6751dedab3c1d0
Source dataset
uspto-grants-2005_05
Patent number
US06900216B2

Reaction notes

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