Reaktion #68757

Reaktionsgleichung

cyclopentane-1,3-dione

toluene

5-bromo-2-cyclopropylphenyl lead triacetate

→

2-(5-bromo-2-cyclopropylphenyl)cyclopentane-1,3-dione

Lösungsmittel

dichloromethane

hydrochloric acid

chloroform

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturthen cooled to room temperature
2. 2
   FiltrationThe resulting biphasic suspension is filtered through diatomaceous earth
3. 3
   Sonstigethe two phases are separated
4. 4
   WaschenThe organic layer is further washed with 2M aqueous hydrochloric acid
5. 5
   Extraktionthe aqueous phase is extracted again with dichloromethane
6. 6
   Waschenwashed with brine
7. 7
   Trocknendried over magnesium sulfate
8. 8
   Einengenthen concentrated in vacuo
9. 9
   SonstigeThe crude product is finally purified by flash column chromatography on silica gel (isohexane/ethyl acetate eluant)

Vorschrift

To a solution of cyclopentane-1,3-dione (0.57 g, 0.0058 mol) and 4-dimethylaminopyridine (3.64 g, 0.030 mol) in chloroform (33 ml) is added toluene (9 ml) then 5-bromo-2-cyclopropylphenyl lead triacetate (3.77 g, 0.0065 mol). This solution is heated at 80° C. for 20 hours then cooled to room temperature and diluted with dichloromethane and 2M aqueous hydrochloric acid. The resulting biphasic suspension is filtered through diatomaceous earth and the two phases are separated. The organic layer is further washed with 2M aqueous hydrochloric acid and the aqueous phase is extracted again with dichloromethane. All organic fractions are combined, washed with brine, dried over magnesium sulfate then concentrated in vacuo. The crude product is finally purified by flash column chromatography on silica gel (isohexane/ethyl acetate eluant) to afford 2-(5-bromo-2-cyclopropylphenyl)cyclopentane-1,3-dione as a pale yellow solid.

Quelle