Triethylamine → Methyl 3-methyl-6-(methylthio)-2-[3-(trifluoromethyl)phenyl]-4-quinolinecarboxylate

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Reaction Steps

DMF (5 drops) was added to a suspension of 3-methyl-6-(methylthio)-2-[3-(trifluoromethyl)phenyl]-4-quinolinecarboxylic acid (2.1 g, 5.56 mmol) in dichloromethane (100 mL). Oxalyl chloride (0.731 mL, 8.35 mmol) was added slowly and the mixture was stirred for 1 h. The solvent was removed under reduced pressure, the residue was redissolved in methanol (50 mL), and triethylamine (1.55 mL, 11.13 mmol) was added slowly. The mixture was stirred overnight at room temperature. The solvent was removed under reduced pressure, the residue was diluted with aqueous saturated NaHCO3, and the aqueous mixture was extracted with ethyl acetate (3 times). The combined organic extracts were washed with brine, dried over Na2SO4, filtered, and concentrated in vacuo. The residue was purified via column chromatography (ISCO, 0-30% ethyl acetate/hexanes) to give methyl 3-methyl-6-(methylthio)-2-[3-(trifluoromethyl)phenyl]-4-quinolinecarboxylate (1.5 g, 69% yield). 1H NMR (400 MHz, DMSO-d6) δ 7.95-8.04 (m, 3H), 7.88 (d, J=8.03 Hz, 1H), 7.69-7.81 (m, 2H), 7.41 (d, J=2.01 Hz, 1H), 4.08 (s, 3H), 2.62 (s, 3H), 2.35 (s, 3H); MS (m/z) 392.1 (M+H+).

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