Hydrochloric Acid → 8-Fluoro-2,3-dihydro-4H-1-benzopyran-4-one

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Reaction Steps

Potassium t-butoxide (2.42 g) was added to a solution of the compound 1-1 (2.20 g) in tetrahydrofuran (100 ml) at room temperature. After stirring for five minutes at the same temperature, beta-propiolactone (2.71 ml) was added. Because of heat generation, the mixture was moved to an ice bath and stirred at the same temperature for one hour. After further stirring at room temperature for four hours, the mixture was made acidic with 1 N hydrochloric acid to terminate the reaction. The aqueous layer was extracted with ethyl acetate, and the organic layer was washed with brine. The organic layer was dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue was crystallized by adding a mixed solvent of 20% ethyl acetate-hexane to obtain the title compound (1.44 g).

Provenance & Evidence