反応 #999

反応方程式

sodium bicarbonate

Bromine

cycloheptanone

ethylene glycol

→

2-bromocycloheptanone ethylene ketal

溶媒

tetrahydrofuran

反応条件

後処理

1. 1
   抽出extracted 3× with diethyl ether
2. 2
   洗浄The combined organic layers were washed with brine
3. 3
   乾燥dried over sodium sulfate
4. 4
   ろ過filtered
5. 5
   濃縮concentrated in vacuo

実験手順

Bromine (44.8 g, 0.28 mol) was added dropwise to a stirred solution of cycloheptanone (28.5 g, 0.25 mol) in a 1:1 solution (300 mL) of ethylene glycol and tetrahydrofuran at room temperature. The mixture was stirred for 5 hours, then poured into aqueous sodium bicarbonate and extracted 3× with diethyl ether. The combined organic layers were washed with brine, dried over sodium sulfate, filtered, and concentrated in vacuo to give 2-bromocycloheptanone ethylene ketal (60 g). A mixture of this crude bromo ketal and a methanolic solution of sodium methoxide (250 mL, 25 wt. % solution) was heated at reflux overnight. The mixture was cooled to ambient temperature, poured into water, and extracted with hexanes. The organic layer was washed with brine, dried over sodium sulfate, filtered, and concentrated in vacuo to afford 2-cycloheptenone ethylene ketal (39 g).

出典