反应详情

A solution of bromine (7.06 ml) in chloroform (70 ml) was added dropwise to a stirred solution of ethyl 6-(4-chlorophenyl)-2,4-dioxo-hex-5-enoate (19.2 g) in chloroform (300 ml) at 5° to 10° C. The solution was stirred for 30 minutes at room temperature then evaporated to a yellow oil. This crude tribromide was dissolved in dimethylsulphoxide (150 ml), and 1,5-diazabicyclo[4.3.0]non-5-ene (16.9 g) was added at 20° to 25° C. The mixture was stirred for 30 minutes at room temperature then diluted with ice-water (300 ml) to precipitate a sticky brown solid. A solution of this crude product in chloroform was passed down a short column of silica-gel (100 g) and then evaporated. The residual solid was washed with ethyl acetate-petroleum ether 60°-80° C., then recrystallised from ethyl acetate-petroleum ether 60°-80° C. to give the title product as yellow needles (mp 146°-149° C.).

1. customthen evaporated to a yellow oil
2. dissolutionThis crude tribromide was dissolved in dimethylsulphoxide (150 ml)
3. addition1,5-diazabicyclo[4.3.0]non-5-ene (16.9 g) was added at 20° to 25° C
4. stirringThe mixture was stirred for 30 minutes at room temperature
5. additionthen diluted with ice-water (300 ml)
6. customto precipitate a sticky brown solid
7. customevaporated
8. washThe residual solid was washed with ethyl acetate-petroleum ether 60°-80° C.
9. customrecrystallised from ethyl acetate-petroleum ether 60°-80° C.