Benzenepropanal → 2,3-dihydro-6-fluoro-2-(2-phenylethyl)-4H-1-benzopyran-4-one

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Reaction Steps

Pyrrolidine (2.4 mL) was added to a solution of 2'-hydroxy-5'-fluoroacetophenone (15.1 g) and 3-phenylpropanal (13.2 mL) in toluene (30 mL), and the mixture heated under reflux in a Dean-Stark apparatus for 3 hours, cooled, diluted with ethyl acetate and washed with aqueous 1N HCl, aqueous 1N NaOH, H2O, brine, dried (Na2SO4), filtered and evaporated, and the residue purified by column chromatography (6:1 hexane/diethyl ether, SiO2) to yield 2,3-dihydro-6-fluoro-2-(2-phenylethyl)-4H-1-benzopyran-4-one (18 gm, Rf=0.3 4:1 hexane/diethyl ether).

Provenance & Evidence