反应详情

A mixture of0.2 mole of dimethyl maleate and 0.1 mole of 5-ethoxy-4-methyl-2-vinyloxazole are heated at 110°-115° C. for 4 hours. The reaction mixture is cooled and 20 ml. of a 25% solution of hydrogen chloride (dry) in absolute methanol added. Addition of ether to the cooled reaction mixture precipitates the hydrochloride salt of the product. The free base is obtained by dissolving the hydrochloride salt in a minimum volume of water, adding solid sodium bicarbonate to pH 6.5 to 7.0 and extracting with chloroform. The combined chloroform extracts are dried over sodium sulfate and concentrated in vacuo to give dimethyl 2-methyl-3-hydroxy-6-vinylpyridine 4,5-dicarboxylate.

1. temperatureThe reaction mixture is cooled
2. customto the cooled reaction mixture
3. customprecipitates the hydrochloride salt of the product
4. customThe free base is obtained
5. extractionextracting with chloroform
6. dry with materialThe combined chloroform extracts are dried over sodium sulfate
7. concentrationconcentrated in vacuo