Reaktion #310709

Reaktionsgleichung

hydrogen chloride

sodium bicarbonate

dimethyl maleate

5-ethoxy-4-methyl-2-vinyloxazole

→

dimethyl 2-methyl-3-hydroxy-6-vinylpyridine 4,5-dicarboxylate

Lösungsmittel

methanol

water

ether

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe reaction mixture is cooled
2. 2
   Sonstigeto the cooled reaction mixture
3. 3
   Sonstigeprecipitates the hydrochloride salt of the product
4. 4
   SonstigeThe free base is obtained
5. 5
   Extraktionextracting with chloroform
6. 6
   TrocknenThe combined chloroform extracts are dried over sodium sulfate
7. 7
   Einengenconcentrated in vacuo

Vorschrift

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.

Quelle