Reaktion #159085

Reaktionsgleichung

H2O2 urea

TFAA

2,7-dibromo-fluoren-9-one

H2O2 urea

→

3,8-Dibromo-benzo[c]chromen-6-one

Ausbeute 134.5%

Lösungsmittel

dichloromethane

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGstirring
2. 2
   workup.WAITwas continued at room temperature for a further 72 hours
3. 3
   FiltrationThe mixture was filtered
4. 4
   Extraktionthe organic phase was extracted with water (50 mL)
5. 5
   Trocknendried over Na2SO4
6. 6
   SonstigeAfter removal of solvent
7. 7
   Temperaturthe residue was heated with 2N NaOH at 80° C. for 10 minutes
8. 8
   Filtrationfiltered
9. 9
   Extraktionthe cooled filtrate extracted with ether
10. 10
    Extraktionextracted with ethyl acetate (200 mL)
11. 11
    workup.ADDITIONHCl (2 mL 4M solution) was added to the ethyl acetate
12. 12
    Temperaturheated for 2 hours
13. 13
    SonstigeThe solvent was removed under vacuum
14. 14
    Sonstigethe residue was recrystallized from ethyl acetate/ethanol

Vorschrift

A solution of TFAA (2.1 mL, 3.15 mmol) in dichloromethane (5 mL) was added dropwise to a suspension of 2,7-dibromo-fluoren-9-one (3.3 g, 10 mmol) and H2O2-urea (1.4 g, 15 mL) in dichloromethane (50 mL). The mixture was stirred at room temperature for 48 hours, a second portion of H2O2-urea was added, and stirring was continued at room temperature for a further 72 hours. The mixture was filtered, the organic phase was extracted with water (50 mL), and dried over Na2SO4. After removal of solvent, the residue was heated with 2N NaOH at 80° C. for 10 minutes, filtered, the cooled filtrate extracted with ether. The aqueous phase was acidified with 2N HCl and extracted with ethyl acetate (200 mL). HCl (2 mL 4M solution) was added to the ethyl acetate and heated for 2 hours. The solvent was removed under vacuum, the residue was recrystallized from ethyl acetate/ethanol to give the final product 3,8-Dibromo-benzo[c]chromen-6-one as a white solid (1.5 g, 40%).

Quelle