Reaktion #2704

Reaktionsgleichung

3,4-dihydro-4,4-dimethyl-7-bromo-1(2H)-naphthalenone

Compound A

3,4-dihydro-4,4-dimethyl-7-bromo-1(2H)-naphthalenone

2-methylthiophene

n-BuLi

→

title compound

Ausbeute 62.3%

1-(5-Methyl-thien-2-yl) 3,4-dihydro-4,4-dimethyl-7-bromo-naphthalene

Ausbeute 62.3%

Lösungsmittel

THF

ether ethylacetate

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigetransferred to a cold (-78° C.) flask
2. 2
   Waschenwashed with water (10 mL), brine (10 mL)
3. 3
   Trocknendried with MgSO4
4. 4
   Sonstigethe solvent was removed by evaporation
5. 5
   workup.DISSOLUTIONThe crude material was dissolved in dichloroethane (20 mL)
6. 6
   workup.ADDITIONpTSA (40 mg) was added
7. 7
   workup.STIRRINGThe mixture was stirred at ambient temperature for 16 hours and at 50° C. for 4 hours
8. 8
   workup.ADDITIONThe reaction mixture was diluted with ether (150 mL)
9. 9
   Waschenwashed with aqueous 10% NaHCO3 (10 mL), brine (10 mL)
10. 10
    Trocknendried with MgSO4
11. 11
    SonstigePurification by chromatography on silica gel

Vorschrift

To a cold (-78° C.) solution of 2-methylthiophene (800 mg, 8.1 mmol) in THF (10 mL) was added n-BuLi (1.6M solution in hexane, 5 mL). The mixture was stirred for 1.5 hours and transferred to a cold (-78° C.) flask containing 3,4-dihydro-4,4-dimethyl-7-bromo-1(2H)-naphthalenone (Compound A, 1.63 g, 6.5 mmol), in THF (15 mL). The mixture was gradually warmed to 0° C. The reaction mixture was diluted with ether:ethylacetate (1:1, 80 mL), washed with water (10 mL), brine (10 mL), dried with MgSO4 and the solvent was removed by evaporation. The crude material was dissolved in dichloroethane (20 mL) and pTSA (40 mg) was added. The mixture was stirred at ambient temperature for 16 hours and at 50° C. for 4 hours. The reaction mixture was diluted with ether (150 mL), washed with aqueous 10% NaHCO3 (10 mL), brine (10 mL) and dried with MgSO4. Purification by chromatography on silica gel gave 1.35 g of the title compound as a white solid.

Quelle