p-Toluenesulfonic acid → 2-Propanol, 1-chloro-3-[(tetrahydro-2H-pyran-2-yl)oxy]-

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Reaction Steps

1-hydroxy-2-(tetrahydropyran-2-yl)oxy-3-chloropropane can be prepared by the following scheme: epichlorohydrin is reacted with acetic acid in the presence of a catalytic amount of iron trichloride to give a mixture of 1-acetyloxy-3-chloropropan-2-ol and 2-acetyloxy-3-chloropropan-1-ol, the major component. The mixture is treated with dihydropyran in the presence of p-toluenesulfonic acid for five hours at 25° C. to give a mixture of 1-acetyloxy-2-(tetrahydropyran-2-yl)oxy-3-chloropropane and 1-(tetrahydropyranyloxy)-2-acetyloxy-3-chloropropane. The mixture is added to a rapidly stirred mixture of aqueous methanol and potassium carbonate at 25° C. and stirred for two hours. Evaporation of the methanol, extraction and drying yields a mixture 1-hydroxy-2-(tetrahydropyran-2-yl)oxy-3-chloropropane and 1-(tetrahydropyran-2-yl)oxy-2-hydroxy-3-chloropropane. Fractional vacuum distillation yields pure 1-hydroxy-2-(tetrahydropyran-2-yl)-oxy-3-chloro-propane since the minor impurity is converted into the more volatile epoxy compound during the distillation procedure.

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