Reaktion #463570

Reaktionsgleichung

6-hydroxy-chromene-2-one

water

1,2-dibromoethane

potassium carbonate

→

product

Ausbeute 26.0%

6-(2-Bromo-ethoxy)-chromen-2-one

Ausbeute 26.0%

Lösungsmittel

ethyl acetate

acetone

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigecan be synthesized in accordance with the procedure
2. 2
   Temperaturat reflux for 48 hours
3. 3
   SonstigeThe cooled reaction mixture
4. 4
   FiltrationThe mixture is filtered
5. 5
   Waschenthe insoluble material is washed with a small amount of additional ethyl acetate
6. 6
   SonstigeThe combined filtrates are separated
7. 7
   Waschenthe aqueous layer is washed several times with fresh ethyl acetate
8. 8
   WaschenThe combined organic layers are washed with 5% aqueous sodium carbonate solution and brine
9. 9
   Trocknendried (sodium sulfate)
10. 10
    Sonstigeevaporated
11. 11
    SonstigeThe residue is purified by flash chromatography (1% methanol in dichloromethane elution)

Vorschrift

A mixture of 6-hydroxy-chromene-2-one, which can be synthesized in accordance with the procedure set forth by T. Harayama, K. Katsuno, H. Nishioka, M. Fujii, Y. Nishita, H. Ishii, and Y. Kaneko, Heterocycles, 1994;39:613, (3.2 g, 19.7 mmol), 1,2-dibromoethane (6.7 mL, 14.6 g, 78 mmol), and potassium carbonate (5.4 g, 39 mmol) in 150 mL of acetone is stirred at reflux for 48 hours. The cooled reaction mixture is added to 1.0 L of water and 250 mL of ethyl acetate. The mixture is filtered, and the insoluble material is washed with a small amount of additional ethyl acetate. The combined filtrates are separated, and the aqueous layer is washed several times with fresh ethyl acetate. The combined organic layers are washed with 5% aqueous sodium carbonate solution and brine, then dried (sodium sulfate), and evaporated. The residue is purified by flash chromatography (1% methanol in dichloromethane elution) to give 1.4 g (26%) of product. A sample recrystallized from ethyl acetate-hexane had melting point (mp) 101-102° C.

Quelle