Sulfuric Acid → 2-[3-(2-Dimethylaminoethoxy)propyl]-5-hydroxy-4,6,7-trimethyl-1,3-benzoxathiole

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Reaction Steps

330 mg of 2-[3-(2-dimethylaminoethoxy)propyl]-5-methoxymethoxy-4,6,7-trimethyl-1,3-benzoxathiole (prepared as described in Example 88) were dissolved in 5 ml of acetic acid, and then 5 drops of 10% v/v aqueous sulfuric acid was added using a Komagome pipette; the mixture was then heated for 5 hours at 70°-75° C. The acetic acid solution was then condensed by evaporation under reduced pressure, and the condensate was poured into ice-water, neutralized with potassium carbonate and extracted with ethyl acetate. The ethyl acetate solution was washed with water and then dried over anhydrous sodium sulfate. The ethyl acetate was then distilled off under reduced pressure. The resulting residue was then subjected to silica gel column chromatography, and the title compound was obtained from the fraction eluted with a 20:1 by volume mixture of ethyl acetate and triethylamine.

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