Toluene → 3-(4-Chlorophenyl)-2,4-dioxo-1-methyl-6-trifluoromethyl-1,2,3,4-tetrahydropyridine

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Reaction Conditions

Reaction Steps

To 200 ml of toluene, 6.7 g (35 mmol) of 4-chlorophenylacetyl chloride and 14.0 g (71 mmol) of ethyl 3-methylamino-4,4,4-trifluorocrotonate were added, followed by stirring for 8 hours under heating and refluxing. After completion of the reaction, the reaction solution was washed with water and a saturated sodium chloride aqueous solution and dried over anhydrous magnesium sulfate. Toluene was distilled off under reduced pressure, and the obtained residue was purified by silica gel column chromatography. This crotonic acid ester was dissolved in 20 ml of THF and dropwise added to a LDA-THF solution [prepared from 54 ml (86 mmol) of a 1.6N-n-butyllithium-hexane solution, 11.3 g (112 mmol) of diisopropylamine and 200 ml of THF] under cooling to -65 to -60° C., followed by stirring at room temperature for 2 hours. After completion of the reaction, excess THF was distilled off, and a 10% citric acid aqueous solution was added thereto. Precipitated crude crystals were washed with ethyl acetate to obtain 3.6 g (yield: 34%) of the desired product.

Provenance & Evidence