反应详情

0.5 g of 3,4-dihydro-2,2-dimethyl-4-(2-pyridyl)-2H-1-benzopyran was dissolved in 10 ml of carbon tetrachloride at room temperature and 0.25 ml of pyridine and 0.12 ml of bromine were added. The mixture was stirred at room temperature for 1 hour, then at 35° C. for 1 hour and finally at 65° C. for 1 hour. After cooling the mixture was washed with sodium bicarbonate solution, the aqueous washings were extracted with dichloromethane and the combined organic phases were washed with water, dried over sodium sulphate and evaporated. The residue was chromatographed on silica gel using 2% (v/v) methanol/dichloromethane for the elution. The product was recrystallized from t-butyl methyl ether to give 230 mg of 6-bromo-3,4-dihydro-2,2-dimethyl)-4-(2-pyridyl)-2H-1-benzopyran of melting point 134°-136° C.

1. waitat 35° C. for 1 hour
2. waitfinally at 65° C. for 1 hour
3. temperatureAfter cooling the mixture
4. washwas washed with sodium bicarbonate solution
5. extractionthe aqueous washings were extracted with dichloromethane
6. washthe combined organic phases were washed with water
7. dry with materialdried over sodium sulphate
8. customevaporated
9. customThe residue was chromatographed on silica gel using 2% (v/v) methanol/dichloromethane for the elution
10. customThe product was recrystallized from t-butyl methyl ether