Potassium Carbonate → ethyl 6-chloro-2-(trifluoromethyl)-2H-chromene-3-carboxylate

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Reaction Conditions

Reaction Steps

A mixture of 5-chlorosalicylaldehyde (20.02 g, 0.128 mole) and ethyl 4,4,4-trifluorocrotonate (23.68 g, 0.14 mole) was dissolved in anhydrous DMF, warmed to 60° C. and treated with anhydrous K2CO3 (17.75 g, 0.128 mole). The solution was maintained at 60° C. for 20 hours, cooled to room temperature, and diluted with water. The solution was extracted with ethyl acetate. The combined extracts were washed with brine, dried over anhydrous MgSO4, filtered and concentrated in vacuo to afford 54.32 g of an oil. The oil was dissolved in 250 mL of methanol and 100 mL of water, whereupon a white solid formed that was isolated by filtration, washed with water and dried in vacuo, to afford the ester as a yellow solid (24.31 g, 62%): mp 62–64° C. 1H NMR (CDCl3/90 MHz) 7.64 (s, 1H), 7.30–7.21 (m, 2H), 6.96 (d, 1H, J=Hz), 5.70 (q, 1H, J=Hz), 4.30 (q, 2H, J=7.2 Hz), 1.35 (t, 3H, J=7.2 Hz).

Provenance & Evidence