反应详情

A solution of Na2CO3.10 H2O (7.3 mmol) in H2O (10 ml) is emulsified under vigorous stirring at about room temperature or slightly elevated temperature with a solution of 2-nitro-3-methoxypyridine (4.25 mmol) and tetrabutylammonium bromide (10.06 mmol) as phase transfer catalyst in methylene chloride (˜20 mL). 2-phenyl-5(4H)-oxazolone (˜60 mmol) is added in several portions during one hour. The layers are separated and the aqueous phase is washed with CH2Cl2. The combined organic solutions are dried with Na2SO4 and is evaporated under reduced pressure. The residue is chromatographed in silica gel starting with petroleum ether to which methylene chloride is gradually added. After recrystallizing, the complex is placed in refluxing methanol to which a catalytic amount of p-toluene sulfonic acid has been added. The sample is refluxed overnight. After cooling and evaporation of the solvent, the above-identified product is isolated.

1. customThe layers are separated
2. washthe aqueous phase is washed with CH2Cl2
3. dry with materialThe combined organic solutions are dried with Na2SO4
4. customis evaporated under reduced pressure
5. customThe residue is chromatographed in silica gel starting with petroleum ether to which methylene chloride
6. additionis gradually added
7. customAfter recrystallizing
8. temperaturein refluxing methanol to which a catalytic amount of p-toluene sulfonic acid
9. additionhas been added
10. temperatureThe sample is refluxed overnight
11. temperatureAfter cooling
12. customevaporation of the solvent
13. customthe above-identified product is isolated