Trifluoroacetic acid → 5-Oxo-2-trifluoromethyl-5,6,7,8-tetrahydro-quinoline-7-carboxylic acid methyl ester

Participants

Reaction Steps

A solution of 3,5-Dioxo-cyclohexanecarboxylic acid methyl ester (3.6 g, 21.16 mmol, preparation as in Journal of the Chemical Society, Perkin Transactions 1 (1976), (13), 1382-4), (Z)-4-Amino-1,1,1-trifluoro-but-3-en-2-one (2.94 g, 21.16 mmol, prepared as in EP 744400 (1996)), trifluoroacetic acid (1.21 g, 10.58 mmol), and ammonium trifluoroacetate (1.39 g, 10.58 mmol) in toluene (50 ml) are heated at reflux temperature in a Dean-Stark apparatus. After reaction completion, the reaction mixture is cooled, diluted with ethyl acetate and then washed successively with saturated aqueous sodium bicarbonate and water. The organic phase is dried over anhydrous sodium sulphate, filtered, and concentrated in vacuo. The residue is purified by flash chromatography, eluting with 4:1 hexane to give the title compound (1.5 g, 68%) as white crystals.

Provenance & Evidence