Potassium Carbonate → Ethyl 1,2-dihydro-6-(trifluoromethoxy)-2-(trifluoromethyl)-3-quinolinecarboxylate

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Reaction Conditions

Reaction Steps

The 2-amino-5-(trifluoromethoxy)benzaldehyde from Step 3 (5.3 g, 26 mmol), anhydrous potassium carbonate (6.9 g, 50 mmol), and ethyl 4,4,4-trifluorocrotonate (7.7 mL, 50 mmol) were mixed in anhydrous dimethylformamide (50 mL) and heated at 90° C. for 6 hours. The reaction was allowed to cool to room temperature and was partitioned between ethyl acetate (200 mL) and water (200 mL). The aqueous layer was extracted with more ethyl acetate (100 mL). The ethyl acetate extracts were combined and washed with brine (200 mL), dried over MgSO4, and concentrated in vacuo yielding an oil (9.6 g). The oil was purified by flash chromatography on silica gel, eluting with ethyl acetate-hexanes (1:1). Fractions containing the desired product were combined, concentrated in vacuo, and the residue recrystallized from ethyl acetate-hexanes to afford the ethyl 1,2-dihydro-6-(trifluoromethoxy)-2-(trifluoromethyl)-3-quinolinecarboxylate as a yellow solid (4.05 g, 32%): mp. 123–125° C. 1H NMR (CDCl3, 300 MHz) 7.65 (s, 1H), 7.02 (m, 2H), 6.60 (m, 1H), 5.10 (m, 1H), 4.60 (brs, 1H), 4.28 (m, 2H), 1.32 (t, 3H, J=7.0 Hz). ESHRMS m/z 356.0698 (M−H, Calc'd 356.0721). Anal. Calc'd for C14H11NO3F6: C, 47.34; H, 3.12; N, 3.94. Found: C, 47.37; H, 3.04; N, 3.93.

Provenance & Evidence