反応 #65431

反応方程式

potassium carbonate

ethyl 2,3-dibromopropionate

catechol

→

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

収率 80.0%

溶媒

acetone

反応条件

後処理

1. 1
   その他at intervals of 15 minutes
2. 2
   温度The reaction mixture is heated
3. 3
   温度at reflux for 18 hours
4. 4
   温度cooled
5. 5
   ろ過filtered through Celite
6. 6
   濃縮The filtrate is concentrated to a residual volume of 60 cm3
7. 7
   抽出hydrolysed with 80 cm3 of water and extracted with diethyl ether
8. 8
   乾燥After drying over magnesium sulfate
9. 9
   濃縮the 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)

実験手順

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##

出典