反应详情

To a stirred and cooled (<10° C.) mixture of 150 g of ethyl 4-(2-pyridinyl)-1-piperazinecarboxylate and 1535 ml of carbon sulfide were added dropwise 32.8 ml of bromine. Upon completion, stirring was continued for 18 hours, while meantime the mixture was allowed to reach room temperature. At a temperature below 20° C., there was added a solution of 70 g of sodium hydroxide solution 10N in 300 ml of water. After stirring for 3 hours at room temperature, the layers were separated. The aqueous phase was extracted twice with trichloromethane. The combined organic phases were washed with water, dried, filtered and evaporated. 46 ml of benzene were added to the residue and the whole was evaporated again. Upon standing for 48 hours, the product was solidified. The oily phase was decanted and the solid product was crystallized twice from 2,2'-oxybispropane at 10° C. It was filtered off and dried, yielding 100 g of ethyl 4-(5-bromo-2-pyridinyl)-1-piperazinecarboxylate; mp. 68° C. (interm. 11).

1. temperaturecooled
2. stirringUpon completion, stirring
3. customto reach room temperature
4. stirringAfter stirring for 3 hours at room temperature
5. customthe layers were separated
6. extractionThe aqueous phase was extracted twice with trichloromethane
7. washThe combined organic phases were washed with water
8. customdried
9. filtrationfiltered
10. customevaporated
11. addition46 ml of benzene were added to the residue
12. customthe whole was evaporated again
13. waitUpon standing for 48 hours
14. customThe oily phase was decanted
15. customthe solid product was crystallized twice from 2,2'-oxybispropane at 10° C
16. filtrationIt was filtered off
17. customdried