Water → diethyl N-(4-ethylcyclohexen-1-yl)-aminomethylenemalonate

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Reaction Steps

A mixture of 12.6 g of 4-ethylcyclohexanone, 17.0 g of diethyl aminomethylenemalonate, and 950 mg of p-toluenesulfonic acid in 170 ml of toluene is heated at reflux for 48 hours with a water separator, under nitrogen atmosphere. The solvent is removed under nitrogen atmosphere and under vacuum, and the residue purified by flash column chromatooraphy on a silica qel column eluted with methylene chloride. The desired product, diethyl N-(4-ethylcyclohexen-1-yl)-aminomethylenemalonate is obtained as an oil. The purified product in 90 ml Dowtherm is aded to 300 ml Dowtherm preheated to 250° under nitrogen atmosphere. After heating at 240°-245° for 4 hours the reaction mixture is cooled and allowed to stand at room temperature overnight. The precipitate which formed is filtered off, washed with hexane and air-dried. Recrystallization form isopropanol after treatment with decolorizing carbon affords ethyl 4-hydroxy-6-ethyl-5,6,7,8-tetrahydroquinoline-3-carboxylate m.p. 218°-220°.

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