Reacción #82231

Ecuación de reacción

hydrochloric acid

sodium bicarbonate

sodium hydroxide

chloroacetone

potassium carbonate

p-toluenesulfonate

5-bromo-2-[(N,N-dimethylcarbamoyl)thio]benzaldehyde

→

2-acetyl-5-bromobenzo[b]thiophene

Rendimiento 40.4%

Disolventes

acetone

acetone

methanol

methyl orthoformate

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturarefluxed
2. 2
   Temperaturaunder heating for 50 minutes
3. 3
   TemperaturaAfter cooling
4. 4
   Otrothe resulting reaction solution
5. 5
   Extracciónextracted with benzene
6. 6
   OtroThe resulting organic layer was dried
7. 7
   Otroto remove the solvent
8. 8
   OtroThe residue thus obtained
9. 9
   Temperaturaby refluxing
10. 10
    Temperaturaunder heating for 1 hour in a stream of nitrogen
11. 11
    TemperaturaAfter cooling
12. 12
    Otrothe resulting reaction solution
13. 13
    Extracciónextracted with benzene
14. 14
    Otrodried
15. 15
    Otroto remove the solvent
16. 16
    OtroThe residue thus obtained
17. 17
    workup.ADDITIONadded dropwise, at room temperature, to a stirred mixture
18. 18
    Otrothe resulting reaction mixture
19. 19
    Temperaturawas refluxed
20. 20
    Temperaturaunder heating for 30 minutes
21. 21
    TemperaturaAfter cooling
22. 22
    Otroinsoluble materials were removed by filtration
23. 23
    Concentraciónthe resulting filtrate was concentrated to dryness
24. 24
    OtroThe thus obtained residue was purified by silica gel column chromatography
25. 25
    Otrothe resulting product was recrystallized from ethanol

Procedimiento

21.0 g of 5-bromo-2-[(N,N-dimethylcarbamoyl)thio]benzaldehyde was dissolved in 50 ml of methyl orthoformate. The resulting solution was mixed with 1.0 g of p-toluenesulfonate, and refluxed under heating for 50 minutes. After cooling, the resulting reaction solution was poured into saturated sodium bicarbonate solution and extracted with benzene. The resulting organic layer was dried to remove the solvent. The residue thus obtained was dissolved in 100 ml of methanol, followed by adding 37 ml of 2N sodium hydroxide and by refluxing under heating for 1 hour in a stream of nitrogen. After cooling, the resulting reaction solution was adjusted to pH 1 with concentrated hydrochloric acid, extracted with benzene, and then dried to remove the solvent. The residue thus obtained was dissolved in 20 ml of acetone and added dropwise, at room temperature, to a stirred mixture consisting of 6.74 g of chloroacetone, 22.1 g of anhydrous potassium carbonate and 150 ml of acetone. After 30 minutes of stirring, the resulting reaction mixture was refluxed under heating for 30 minutes. After cooling, insoluble materials were removed by filtration, and the resulting filtrate was concentrated to dryness. The thus obtained residue was purified by silica gel column chromatography using toluene as an elution solvent and the resulting product was recrystallized from ethanol to obtain 7.5 g of 2-acetyl-5-bromobenzo[b]thiophene.

Fuente