m-Chloroperbenzoic acid → 2-(((4-((5,5-dimethyl-1,3-dioxan-2-yl)methoxy)-3-methylpyridin-2-yl)methyl)sulfinyl)-1H-benzimidazole

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Reaction Conditions

Reaction Steps

The 2-(((4-((5,5-dimethyl-1,3-dioxan-2-yl)methoxy)-3-methylpyridin-2-yl)methyl)thio)-1H-benzimidazole (599 mg, 1.5 mmol) obtained by the step (1e) was mixed with methanol (5 ml) and toluene (15 ml), and the mixture was cooled to −50° C. 3-chloroperbenzoic acid (358 mg, 1.35 mmol, as the content was regarded as 65%) dissolved in a solvent mixture of methanol and toluene was slowly added dropwise to the mixture, and stirred at −47° C. to −70° C. for 3 hours. A saturated aqueous solution of sodium hydrogen carbonate was added to the reaction mixture, which was then extracted with ethyl acetate. The organic layer was washed with a saturated saline solution, dried over potassium carbonate, and the solvent was distilled off. The residue was purified with silica gel column chromatography (NH silica gel: 40 g, elution solvent: dichloromethane/heptane=7/3→methanol/dichloromethan=3/97 to 1/9). To the obtained product, heptane (20 ml) and diethyl ether (2 ml) were added, the precipitate was obtained by filtration. In this manner, the title compound (475 mg, yield: 76.2%) was obtained as a light orange solid.

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