反应详情

A solution consisting of methyl 3-acetyl-4-hydroxy-benzoate (16 g) and methyl nicotinate (23 g) in dioxane (100 ml) was slowly added at room temperature under stirring to a suspension of sodium hydride 50% (12 g) in dioxane (60 ml). The solution was kept for 6 hours at 80° C., then cooled, diluted with petroleum ether (200 ml), and filtered. The product obtained was dissolved in water and treated with acetic acid; the precipitate obtained was washed with water and crystallised with methylene chloride/methanol to give (2-hydroxy-5-carbomethoxy-benzoyl)-nicotinoylmethane (17.2 g; m.p. 200°-202° C.) which was then treated with ethanol (300 ml) containing concentrated hydrochloric acid 1% at reflux temperature for 2 hours. After concentration under vacuum, dilution with water, neutralisation with sodium acetate, the precipitate was filtered. The raw 6-carbomethoxy-2-(3'-pyridyl)-chromone (15.1 g) was hydrolysed with the stoichiometric quantity of potassium hydroxide 1% in ethanol 95% at reflux temperature for an hour. After cooling, dilution with water (600 ml), neutralisation with acetic acid, the precipitate was collected, to obtain, after crystallisation from dimethylformamide, 6-carboxy-2-(3'-pyridyl)-chromone (9.8 g; m.p.> 350° C.); I.R. (KBr): νC=O (carboxy) 1680 cm-1, νC=O (chromone) 1630 cm-1, 1610 cm-1, γC-H (meta-substituted pyridine) 770 cm-1, 696 cm-1.

1. additionwas slowly added at room temperature
2. temperaturecooled
3. filtrationfiltered
4. customThe product obtained
5. customthe precipitate obtained
6. washwas washed with water
7. customcrystallised with methylene chloride/methanol