Reaktion #65431

Reaktionsgleichung

potassium carbonate

ethyl 2,3-dibromopropionate

catechol

→

Ethyl 2,3-dihydro-1,4-benzodioxin-2-carboxylate

Ausbeute 80.0%

Lösungsmittel

acetone

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeat intervals of 15 minutes
2. 2
   TemperaturThe reaction mixture is heated
3. 3
   Temperaturat reflux for 18 hours
4. 4
   Temperaturcooled
5. 5
   Filtrationfiltered through Celite
6. 6
   EinengenThe filtrate is concentrated to a residual volume of 60 cm3
7. 7
   Extraktionhydrolysed with 80 cm3 of water and extracted with diethyl ether
8. 8
   TrocknenAfter drying over magnesium sulfate
9. 9
   Einengenthe ethereal phase is concentrated under reduced pressure
10. 10
    workup.DISTILLATIONthe crude product is purified by distillation under reduced pressure (b.p.=155° C. under 15 mm Hg)

Vorschrift

Under a nitrogen atmosphere, add 18.2 g (131 mmol) of dry potassium carbonate and 13 g (50 mmol) of ethyl 2,3-dibromopropionate in succession to a solution of 20 g (18 1 mmol) of catechol dissolved in 120 cm3 of anhydrous acetone. The operation is repeated four times in succession at intervals of 15 minutes. The reaction mixture is heated at reflux for 18 hours, and then cooled and filtered through Celite. The filtrate is concentrated to a residual volume of 60 cm3, then hydrolysed with 80 cm3 of water and extracted with diethyl ether. After drying over magnesium sulfate, the ethereal phase is concentrated under reduced pressure and the crude product is purified by distillation under reduced pressure (b.p.=155° C. under 15 mm Hg). Ethyl 2,3-dihydro-1,4-benzodioxin-2-carboxylate is thereby obtained in a yield of 80%. nD25 =1.5214 ##STR25##

Quelle