Reaktion #68752

Reaktionsgleichung

5-bromo-2-trifluoromethoxybenzaldehyde

boron trifluoride etherate

water

boron trifluoride etherate

1,2-bis(trimethylsiloxy)cyclobutene

→

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

Lösungsmittel

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGAfter stirring for 24 hours at room temperature the reaction mixture
2. 2
   Sonstigeis then quenched with saturated aqueous ammonium chloride solution (50 ml)
3. 3
   Extraktionextracted with dichloromethane (2×50 ml)
4. 4
   ExtraktionThe crude product is extracted from the organic phase
5. 5
   Waschenby washing with 0.5 M aqueous potassium carbonate solution (×3)
6. 6
   ExtraktionFinal extraction with dichloromethane (×3)
7. 7
   Waschenby washing with brine
8. 8
   Trocknenthen drying over magnesium sulfate and filtration
9. 9
   EinengenConcentration in vacuo
10. 10
    Sonstigegives a crude product which
11. 11
    Sonstigeis purified by preparative reverse phase HPLC

Vorschrift

To a solution of 5-bromo-2-trifluoromethoxybenzaldehyde (2.0 g, 7.43 mmol) in anhydrous dichloromethane (40 ml) at room temperature is added boron trifluoride etherate (1.13 ml, 8.92 mmol) then 1,2-bis(trimethylsiloxy)cyclobutene (2.86 ml, 11.2 mmol). The mixture is stirred at room temperature for 23 hours, followed by addition of distilled water (1.2 ml) and additional boron trifluoride etherate (14.1 ml, 112 mmol). After stirring for 24 hours at room temperature the reaction mixture is then quenched with saturated aqueous ammonium chloride solution (50 ml) and extracted with dichloromethane (2×50 ml). The crude product is extracted from the organic phase by washing with 0.5 M aqueous potassium carbonate solution (×3), then acidified to pH 1 with concentrated hydrochloric acid. Final extraction with dichloromethane (×3) is followed by washing with brine then drying over magnesium sulfate and filtration. Concentration in vacuo gives a crude product which is purified by preparative reverse phase HPLC to afford 2-(5-bromo-2-trifluoromethoxyphenyl)cyclopentane-1,3-dione.

Quelle