Dimethylformamide → 5-Methoxy-3-stilbene carboxylic acid methyl ester

Beteiligte Stoffe

Reaktionsschritte

To a slurry of 1.0 mole of sodium hydride in one liter of N,N-dimethylformamide is added 1.0 mole of diethyl benzylphosphonate. The reaction mixture is stirred for one hour and then a solution of 1.0 mole of 3-methoxyisophthalaldehydic acid methyl ester in a minimal amount of dimethylformamide is added. The reaction mixture is stirred for several hours and is then added to ether-water. The ether extract is washed several times with water, dried over magnesium sulfate and evaporated to a residue. The residue is purified via crystallization from hexane to yield 5-methoxy-3-stilbene carboxylic acid methyl ester. The free acid is obtained by refluxing a solution of 1.0 mole of the methyl ester in one liter in 1 N methanolic sodium hydroxide for 4-5 hours. The reaction mixture is evaporated to a residue which is added to ethyl acetate. The ethyl acetate solution is extracted with several portions of water. The combined aqueous extract is neutralized with 1 N hydrochloric acid and extracted with several portions of ethyl acetate. This organic extract is dried over magnesium sulfate and evaporated to a residue. The residue is purified by crystallization from hexane to yield 5-methoxy-3-stilbene carboxylic acid.

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