Reaktion #2270787

Reaktionsgleichung

iodine

4-bromobenzo[b]thiophene

N-methoxy-N-methylpropionamide

4-bromobenzo[b]thiophene

magnesium

→

1-(benzo[b]thiophen-4-yl)propan-1-one

Lösungsmittel

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeprepared in a manner similar to
2. 2
   Temperaturheat
3. 3
   Sonstigethe reaction
4. 4
   Temperaturat reflux temperature over 20 minutes
5. 5
   Temperaturthe mixture was heated
6. 6
   Temperaturunder reflux for 10 minutes
7. 7
   Temperaturthe mixture was heated
8. 8
   Temperaturunder reflux for 30 minutes
9. 9
   Temperaturit was cooled to ambient temperature
10. 10
    Sonstigequenched by the addition of 2M hydrochloric acid (25 ml)
11. 11
    Sonstigethe tetrahydrofuran was removed in vacuo
12. 12
    workup.ADDITIONthe residue was diluted with water (50 ml)
13. 13
    Extraktionthe product was extracted into ethyl acetate (50 ml)
14. 14
    WaschenThe extract was washed with saturated aqueous sodium chloride solution (2×50 ml)
15. 15
    Trocknendried (Na2SO4)
16. 16
    Sonstigethe solvents were removed in vacuo
17. 17
    SonstigeThe residue was purified by flash chromatography over silica using
18. 18
    workup.ADDITIONa 97:3 mixture of petroleum ether (b.p. 40-60° C.) and ethyl acetate as eluant
19. 19
    Sonstigethe solvents removed in vacuo

Vorschrift

Approximately 3 ml of a solution of 4-bromobenzo[b]thiophene (1.85 g; prepared in a manner similar to that described in Bull. Soc. Chim. Fr., 1966, 111, 3667-3674) in tetrahydrofuran (20 ml) was added under nitrogen to a mixture of magnesium turnings (0.22 g) and tetrahydrofuran (2 ml). 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, the mixture was heated under reflux for 10 minutes, then it was cooled to ambient temperature. A solution of N-methoxy-N-methylpropionamide (1.01 g) in tetrahydrofuran (10 ml) was added, the mixture was heated under reflux for 30 minutes, then it was cooled to ambient temperature and quenched by the addition of 2M hydrochloric acid (25 ml). The mixture was allowed to stand at ambient temperature for 18 hours, then the tetrahydrofuran was removed in vacuo, the residue was diluted with water (50 ml) and the product was extracted into ethyl acetate (50 ml). The extract was washed with saturated aqueous sodium chloride solution (2×50 ml), dried (Na2SO4), and the solvents were removed in vacuo. The residue was purified by flash chromatography over silica using a 97:3 mixture of petroleum ether (b.p. 40-60° 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 (0.615 g) as a colourless oil which was used without further purification.

Quelle