反应详情

Piperidine (200 ml) was added to a solution consisting of methyl 3-hydroxy-4-acetyl-benzoate (15 g) and salicylaldehyde 15 g) in absolute ethanol (400 ml); the mixture was kept at reflux temperature for 40 hours. After cooling, acidification with hydrochloric acid and extraction with ethylacetate, the organic phase was washed with K2CO3 5%, and with water, then evaporated to dryness. The residue, so obtained (11 g), was dissolved in n-amylic alcohol (200 ml) by adding SeO2 (11 g) and the solution was kept at reflux temperature for 18 hours. After cooling, the residue was filtered off and the amylic alcohol was distilled in a steam current: the residue of the distillation was recovered by extraction with chloroform, to give, after crystallisation from ethanol, 7-carbomethoxy-2'-hydroxy-flavone (6.3 g), which was reacted in dimethylformamide (30 ml) with 2-bromo-propane (3.5 g) and anhydrous potassium carbonate (4 g) at 70° C for 18 hours. After cooling, the mixture was diluted with water (200 ml), and then filtered, so obtaining 7-carbomethoxy-2'-isopropoxy-flavone (7.9 g) which was subsequently hydrolyzed by treatment with the stoichiometric quantity of a solution of potassium hydroxide 1% in ethanol 95% at reflux temperature for 30 minutes. After cooling, acidification with acetic acid, dilution with water, filtration, and subsequent crystallisation from ethanol, 7-carboxy-2'-isopropoxy-flavone (5.7 g) was obtained.

1. temperatureat reflux temperature for 40 hours
2. temperatureAfter cooling
3. extractionacidification with hydrochloric acid and extraction with ethylacetate
4. washthe organic phase was washed with K2CO3 5%
5. customwith water, then evaporated to dryness
6. customThe residue, so obtained (11 g)
7. temperatureat reflux temperature for 18 hours
8. temperatureAfter cooling
9. filtrationthe residue was filtered off
10. distillationthe amylic alcohol was distilled in a steam current
11. distillationthe residue of the distillation
12. customwas recovered by extraction with chloroform
13. customto give
14. customafter crystallisation from ethanol, 7-carbomethoxy-2'-hydroxy-flavone (6.3 g), which
15. customwas reacted in dimethylformamide (30 ml) with 2-bromo-propane (3.5 g) and anhydrous potassium carbonate (4 g) at 70° C for 18 hours
16. temperatureAfter cooling
17. filtrationfiltered
18. temperatureat reflux temperature for 30 minutes
19. temperatureAfter cooling
20. filtrationacidification with acetic acid, dilution with water, filtration, and subsequent crystallisation from ethanol