反应详情

[2-(1-Cyclohexenyl)-4-oxo-4H-[1]-benzopyran-8-yl]acetic acid (2.84 g) was dissolved in dimethylformamide (30 ml) and carbodiimidazole (1.78 g) was added to the solution. After stirring at room temperature for 2 hours, 2,2-dimethyl-propanol (0.88 g) was added. After stirring at 60° C. for 4 hours, water was added and the mixture was extracted with ethyl acetate. The extracted layer was washed with water, dried and concentrated. The residue was purified by silica gel column chromatography to obtain the title compound (0.82 g), yield 23%, m.p. 138°-139° C. (recrystallized from hexane-ethyl acetate).

1. stirringAfter stirring at 60° C. for 4 hours
2. extractionthe mixture was extracted with ethyl acetate
3. washThe extracted layer was washed with water
4. customdried
5. concentrationconcentrated
6. customThe residue was purified by silica gel column chromatography
7. customto obtain
8. customthe title compound (0.82 g), yield 23%, m.p. 138°-139° C. (recrystallized from hexane-ethyl acetate)