反应详情

To a solution of ethyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate (14.81 g, 0.0625 mole) in 30 ml of ethylene bromide was added dropwise at 0° a solution of aluminum bromide (25 g, 0.094 mole) in 20 ml of ethylene bromide. After stirring for 41/2 hours, the solution was poured into a mixture of ice and water. The resultant mixture was extracted three times with ether. The ether extracts were combined and successively washed twice with water, twice with aqueous sodium bicarbonate, twice with aqueous sodium chloride, and then dried over anhydrous magnesium sulfate. The ether was then removed by evaporation, leaving a residue. The residue was dissolved in n-hexane, and 1,5-diazabicyclo[5.4.0] undec-5-ene was added to the solution. Dimethylformamide was added as a cosolvent. The solution was poured into dilute aqueous hydrochloric acid at 0°. The resultant mixture was extracted with ether. The ether extract was washed with water, aqueous sodium bicarbonate, aqueous sodium chloride, and then dried. The ether was removed, and the residue was distilled under reduced pressure to afford ethyl 3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate (16.28 g, 87% yield); bp, 104-106°/0.28 mm.

1. extractionThe resultant mixture was extracted three times with ether
2. washsuccessively washed twice with water, twice with aqueous sodium bicarbonate, twice with aqueous sodium chloride
3. dry with materialdried over anhydrous magnesium sulfate
4. customThe ether was then removed by evaporation
5. customleaving a residue
6. extractionThe resultant mixture was extracted with ether
7. extractionThe ether extract
8. washwas washed with water, aqueous sodium bicarbonate, aqueous sodium chloride
9. customdried
10. customThe ether was removed
11. distillationthe residue was distilled under reduced pressure