1,1'-Biphenyl, mixt. with 1,1'-oxybis(benzene) → Ethyl 8-chloro-4-oxo-5-(trifluoromethyl)-1,4-dihydroquinoline-3-carboxylate

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Reaction Conditions

Reaction Steps

A 3-neck, 1 L flask was charged with Dowtherm® (200 mL, 8 mL/g), which was degassed at 200° C. for 1 h. The solvent was heated to 260° C. and charged in portions over 10 min with diethyl 2-((2-chloro-5-(trifluoromethyl)phenylamino)methylene)malonate (6B) (25 g, 0.07 mol). The resulting mixture was stirred at 260° C. for 6.5 hours (h) and the resulting ethanol byproduct removed by distillation. The mixture was allowed to slowly cool to 80° C. Hexane (150 mL) was slowly added over 30 minutes (min), followed by an additional 200 mL of hexane added in one portion. The slurry was stirred until it had reached room temperature. The solid was filtered, washed with hexane (3×150 mL), and then dried under vacuum to provide ethyl 8-chloro-4-oxo-5-(trifluoromethyl)-1,4-dihydroquinoline-3-carboxylate (6A) as a tan solid. 1H NMR (400 MHz, DMSO-d6) δ 11.91 (s, 1H), 8.39 (s, 1H), 8.06 (d, J=8.3 Hz, 1H), 7.81 (d, J=8.4 Hz, 1H), 4.24 (q, J=7.1 Hz, 2H), 1.29 (t, J=7.1 Hz, 3H).

Provenance & Evidence