Benzyltrimethylammonium hydroxide → 8-(3-[2-t-butylphenoxy]-2-hydroxypropoxy)-4-oxo-4H-1-benzopyran-2-carboxylic acid

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A mixture of 16.7 parts of ethyl 8-hydroxy-4-oxo-4H-1-benzopyran-2-carboxylate, 14.7 parts of 3-(2-t-butylphenoxy)-1,2 -epoxypropane, 50 parts of dimethyl formamide, and 0.1 parts of benzyltrimethyl ammonium hydroxide was boiled under reflux for 3 hours, evaporated to leave a dark brown oil, and treated with ethyl acetate, which was then washed with 2% sodium hydroxide solution, and water, dried, and evaporated to an oil. The oil was chromatographed on a silica column with chloroform as eluent to give a gummy solid, which was boiled with an aqueous ethanolic solution of sodium bicarbonate. The mixture was acidified to give a solid, which was recrystallised from ethanol after treatment with charcoal to give 4.6 parts of 8-(3-[2-t-butylphenoxy]-2-hydroxypropoxy)-4-oxo-4H-1-benzopyran-2-carboxylic acid as a cream solid, mp. 227°-228° (decomp.).

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