890839-66-4

General procedure for the synthesis of 8-trifluoromethylbenzodihydropyran-4-one using the compound (CAS: 890839-64-2) as starting material: a mixed solution of Example 18A (24.1 g, 103 mmol) with sulfuric acid (12 mL, 225 mmol) in 200 mL of trifluoroacetic acid was stirred at room temperature for 3 days. Upon completion of the reaction, the reaction mixture was slowly poured into ice water and extracted with dichloromethane (2 x 200 mL). The organic phases were combined and washed with 200 mL of saturated aqueous sodium bicarbonate followed by drying with anhydrous magnesium sulfate. The desiccant was removed by filtration and the filtrate was concentrated under reduced pressure. Purification by silica gel column chromatography (eluent: 15% ethyl acetate/hexane) afforded the target product 8-trifluoromethylbenzodihydropyran-4-one (7.21 g, 33.4 mmol, 32% yield). Mass spectrum (DC1/NH3) m/z 216 (M + NH4 - H2O)+.

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