反应详情

Phosphorous oxychloride (2.86 ml) was added very slowly at 0° C. to dry N,N-dimethylformamide (40 ml) and the mixture was left under stirring at room temperature for 35 minutes. After that a solution of 8-nitro-4-oxo-4H-1-benzopyran-2-carboxamide (1.515 g, 6.47 mmol) in N,N-dimethylformamide (10 ml) was added and the mixture was left under stirring at room temperature for 18 h. After this time, the reaction mixture was poured onto an ice-water mixture (100 ml) and extracted with ethyl acetate (4×40 ml). After drying and removing the solvents under reduced pressure, a residue was obtained which was purified by chromatography through a silica gel column. Eluting with hexane:chloroform, 7:3, 1.094 g of the title product were recovered (78% yield).

1. waitthe mixture was left
2. waitthe mixture was left
3. stirringunder stirring at room temperature for 18 h
4. extractionextracted with ethyl acetate (4×40 ml)
5. customAfter drying
6. customremoving the solvents under reduced pressure
7. customa residue was obtained which
8. customwas purified by chromatography through a silica gel column
9. washEluting with hexane
10. customchloroform, 7:3, 1.094 g of the title product were recovered (78% yield)