反应详情

30 g of 1,3-dibromopropane was added dropwise at ambient temperature to a suspension of 30 g of sodium 3-methyl-4-oxo-2-phenyl-4H-1-benzopyran-8-carboxylate in 150 ml of dimethylformamide and 35 ml of water. The reaction mixture was stirred at ambient temperature for 5 days. 100 ml of water was added and stirring was continued for a further 15 minutes. The precipitate was filtered off by suction, washed with water and purified by flash chromatography on silica gel, eluting with chloroform:ethyl acetate 95:5. The collected fractions were evaporated to dryness in vacuo and the residue was recrystallized from ethanol to give 27.7 g of the title compound, m.p. 114-115° C.

1. stirringstirring
2. waitwas continued for a further 15 minutes
3. filtrationThe precipitate was filtered off by suction
4. washwashed with water
5. custompurified by flash chromatography on silica gel
6. washeluting with chloroform:ethyl acetate 95:5
7. customThe collected fractions were evaporated to dryness in vacuo
8. customthe residue was recrystallized from ethanol