Acetone → ethyl 4-oxo-7-(3-[2-propylphenoxy]-propoxy)-4H-1-benzopyran-2-carboxylate

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A mixture of 58.5 parts of ethyl 7-hydroxy-4-oxo-4H-1-benzopyran-2-carboxylate, 64.25 parts of 2-(3-bromopropoxy) propylbenzene, 17.25 parts of anhydrous potassium carbonate and 1000 parts of acetone was refluxed, with stirring, for 21/2 days and the hot solution filtered. The residue was washed with hot acetone and the combined filtrates evaporated to give an oil which was dissolved in chloroform. The resulting solution was washed with 1N sodium hydroxide solution and then dried. Evaporation of the chloroform gave an oil which yielded a solid on crystallisation from ethanol. The solid was chromatographed on silica gel, eluting with a 1:1 mixture of ethyl acetate and 40/60 light petroleum ether. Evaporation of the eluent and crystallisation of the resulting residue from ethanol gave 18.4 parts of ethyl 4-oxo-7-(3-[2-propylphenoxy]-propoxy)-4H-1-benzopyran-2-carboxylate, m.pt. 75°-76.5°.

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