反应详情

温度

-5 °C

1.62 g of 4-(5-amino-2-pyridyl)-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile were suspended in 12 ml of concentrated hydrochloric acid, 30 g of ice and 18 ml of N-methylpyrrolidone. The mixture was cooled to -5° C. and 0.44 g of sodium nitrite in 5 ml of water was added dropwise while maintaining the temperature below 0° C. After completion of the addition the mixture was allowed to warm to room temperature and was then heated at 40° C. for 1 hour. The mixture was extracted with ethyl acetate and the extract was evaporated. The residue was taken up in diethyl ether and water and the separated organic phase was washed with water, dried over sodium sulphate and evaporated. The residue was chromatographed on silica gel using ethyl acetate/petroleum ether (1:1) and ethyl acetate for the elution to give 270 mg of 4-(5-chloro-2-pyridyl)-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile and 254 mg of 4 -(5-hydroxy-2-pyridyl)-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile.

1. temperaturewhile maintaining the temperature below 0° C
2. additionAfter completion of the addition the mixture
3. temperatureto warm to room temperature
4. temperaturewas then heated at 40° C. for 1 hour
5. extractionThe mixture was extracted with ethyl acetate
6. customthe extract was evaporated
7. washwater and the separated organic phase was washed with water
8. dry with materialdried over sodium sulphate
9. customevaporated
10. customThe residue was chromatographed on silica gel
11. washfor the elution