m-Chloroperbenzoic acid → 2-(4-(2,2-Dimethyl-1,3-dioxan-5-yl)methoxy-3,5-dimethylpyridin-2-yl)methylsulfinyl-1H-benzimidazole

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Reaction Steps

To a toluene (20 ml)-methanol (2 ml) solution of the 2-(((4-((2,2-dimethyl-1,3-dioxan-5-yl)methoxy)-3,5-dimethylpyridin-2-yl)methyl)thio)-1H-benzimidazole (424 mg, 1.03 mmol) obtained in the step (11g), a toluene (1 ml)-methanol (1 ml) solution of 3-chloroperbenzoic acid (246 mg, 0.927 mmol as the content was regarded as 65%) was added dropwise at −65° C. for 5 minutes in a nitrogen atmosphere. The mixture was stirred for 45 minutes in the same conditions. To the reaction mixture, a saturated aqueous solution of sodium hydrogen carbonate was added and the mixture was extracted with ethyl acetate. The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated. The residue was purified by silica gel column chromatography (NH silica gel: 20 g, elution solvent: dichloromethane, dichloromethane/methanol=10/1). The fractions containing the title compound were collected with ethyl acetate and concentrated. To the residue, diethyl ether was added. The resulting precipitate was collected by filtration and washed with diethyl ether to obtain the title compound (274 mg, yield: 61.9%) as a white solid.

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