Benzyltrimethylammonium hydroxide → 6-[2-hydroxy-3-(2-propylphenoxy)propoxy]-4-oxo-4H-1-benzopyran-2-carboxylic acid

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Reaction Steps

A mixture of 19.2 parts of 1,2-epoxy-3-(2-propylphenoxy) propane, 23.4 parts of ethyl 6-hydroxy-4-oxo-4H-1-benzopyran-2-carboxylate and 0.1 parts of benzyl trimethylammonium hydroxide in 50 parts of dimethyl formamide was heated under reflux for 3 hours. The solvent was evaporated under reduced pressure and the oil remaining dissolved in ethyl acetate. The solution was washed with dilute sodium hydroxide and water, dried over magnesium sulphate, filtered and evaporated to leave an oil. The oil was dissolved in ethyl alcohol, 20.0 parts of sodium bicarbonate were added, and the mixture was boiled for 2 hours, during which time water was added and the ethyl alcohol allowed to boil off. The aqueous solution was washed with ethyl acetate and acidified with dilute hydrochloric acid to give a brown precipitate which was collected and crystallised twice from ethyl alcohol to yield 10.5 parts of 6-[2-hydroxy-3-(2-propylphenoxy)propoxy]-4-oxo-4H-1-benzopyran-2-carboxylic acid, melting point 164°-166° C.

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