Potassium Carbonate → ethyl 6-chloro-5,7-dimethyl-2-(trifluoromethyl)-2H-chromene-3-carboxylate

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To a solution of 3-chloro-6-hydroxy-2,4-dimethylbenzaldehyde (6.9 g, 37.4 mmol) in 80 mL of DMF was added dried finely powdered K2CO3 (11.36 g, 82.2 mmol). With mechanical stirring, the reaction was heated to 65° C. To the suspension was added dropwise ethyl trifluorocrotonate (7.54 g, 44.9 mmol). The stirring reaction was heated at 90° C. for 1.5 h. K2CO3 was filtered from the cooled reaction. From the reaction under vacuum, DMF was removed. The resulting residue was dissolved in 400 mL EtOAc. The organic solution was washed with 100 mL 1 M KHSO4, 70 mL of satd. KHCO3, 100 mL brine, followed by drying over MgSO4, and concentrating under vacuum. The crude desired product (13.8 g) of was isolated. After employing flash chromatography conditions, pure compound (9.8 g, 78%) of was isolated and its structure confirmed by NMR and LC-MS.

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