反応 #167031

反応方程式

H2O2 urea

TFAA

2,7-dibromo-fluoren-9-one

H2O2 urea

→

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

収率 134.5%

溶媒

dichloromethane

dichloromethane

反応条件

後処理

1. 1
   workup.STIRRINGstirring
2. 2
   workup.WAITwas continued at room temperature for a further 72 hours
3. 3
   ろ過The mixture was filtered
4. 4
   抽出the organic phase was extracted with water (50 mL)
5. 5
   乾燥dried over Na2SO4
6. 6
   その他After removal of solvent
7. 7
   温度the residue was heated with 2N NaOH at 80° C. for 10 minutes
8. 8
   ろ過filtered
9. 9
   抽出the cooled filtrate extracted with ether
10. 10
    抽出extracted with ethyl acetate (200 mL)
11. 11
    workup.ADDITIONHCl (2 mL 4M solution) was added to the ethyl acetate
12. 12
    温度heated for 2 hours
13. 13
    その他The solvent was removed under vacuum
14. 14
    その他the residue was recrystallized from ethyl acetate/ethanol

実験手順

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%).

出典