Dimethylformamide → 1,3,5-Tricarbethoxy-1,4-dihydro-2,6-dimethyl-4-(2-trifluoromethylphenyl)pyridine

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Reaction Steps

To 1.2 g. of sodium hydride (57% dispersion in mineral oil) suspended in tetrahydrofuran is added dropwise with stirring a solution of 10 g. of 3,5-dicarbethoxy-1,4-dihydro-2,6-dimethyl-4-(2-trifluoromethylphenyl)pyridine in tetrahydrofuran. The mixture is heated on a steam bath for 15 minutes, then it is cooled and enough dimethylformamide is added to dissolve the solid which has separated. To the resulting solution is added dropwise 3.04 g. of ethyl chloroformate and the reaction mixture is stirred at 25° for 15 minutes then heated on a steam bath for 12 hours. The mixture is filtered and concentrated to give an oil which is dissolved in acetonitrile. The solution is extracted with petroleum ether then concentrated to give an oil which is stirred with petroleum ether. The solid formed is filtered and the filtrate is concentrated in vacuo to give an oil which is chromatographed on an alumina "dry column" with methylene chloride as eluant to give 1,3,5-tricarbethoxy-1,4-dihydro-2,6-dimethyl-4-(2-trifluoromethylphenyl)pyridine, m.p. 56°-58°C.

Provenance & Evidence