Reaktion #1808544

Reaktionsgleichung

dicyclopropylketone

3,5-di-tert-butyl-4-hydroxyacetophenone

di-iso-propyl ethylamine

trimethylsilyl trifluoromethanesulphonate

→

3,5-di-tert-butyl-4-hydroxyphenyl-3,3-dicyclopropylprop-2-en-1-one

Lösungsmittel

methylene chloride

methylene chloride

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturto warm to ambient temperature over 1 hour
2. 2
   TemperaturThe mixture is cooled again to -78° C.
3. 3
   workup.STIRRINGAfter stirring for 1 hr
4. 4
   Waschenthe mixture is washed with 1N aqueous hydrochloric acid
5. 5
   Sonstigethe solvents are removed under reduced pressure
6. 6
   workup.DISSOLUTIONThe residue is dissolved in 50 ml of methanol-1N aqueous hydrochloric acid
7. 7
   workup.STIRRINGstirred for 1 hr at room temperature
8. 8
   EinengenThe mixture is concentrated under reduced pressure
9. 9
   Sonstigepartitioned between methylene chloride and water
10. 10
    WaschenThe organic phase is washed with aqueous sodium bicarbonate, brine
11. 11
    Trocknendried over sodium sulphate
12. 12
    SonstigeThe solvents are evaporated
13. 13
    Sonstigethe residue is purified by flash chromatography (10% ethyl acetate in hexane)
14. 14
    Sonstigethe product is recrystallized from hexane

Vorschrift

A stirred solution of 4 g of 3,5-di-tert-butyl-4-hydroxyacetophenone in 250 ml of dry methylene chloride is cooled to -78° C. and 7.3 ml di-iso-propyl ethylamine (i-Pr2EtN) is added followed by 8.1 ml of trimethylsilyl trifluoromethanesulphonate (TMSOTf). The mixture is stirred at -78° C. for 10 minutes and is allowed to warm to ambient temperature over 1 hour. The mixture is cooled again to -78° C., and 3.6 ml of dicyclopropylketone is added followed by 32 ml of 1M titanum tetrachloride solution in methylene chloride. After stirring for 1 hr, the mixture is washed with 1N aqueous hydrochloric acid and the solvents are removed under reduced pressure. The residue is dissolved in 50 ml of methanol-1N aqueous hydrochloric acid and stirred for 1 hr at room temperature. The mixture is concentrated under reduced pressure and partitioned between methylene chloride and water. The organic phase is washed with aqueous sodium bicarbonate, brine and dried over sodium sulphate. The solvents are evaporated and the residue is purified by flash chromatography (10% ethyl acetate in hexane), and the product is recrystallized from hexane to give 1-(3,5-di-tert-butyl-4-hydroxyphenyl-3,3-dicyclopropylprop-2-en-1-one as an orange solid.

Quelle