m-Chloroperbenzoic acid → 2-(((4-(5,7-dioxaspiro[2.5]oct-6-ylmethoxy)-3-methylpyridin-2-yl)methyl)sulfinyl)-1H-benzimidazole

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Reaction Conditions

Reaction Steps

The 2-(((4-(5,7-dioxaspiro[2.5]oct-6-ylmethoxy)-3-methylpyridin-2-yl)methyl)thio)-1H-benzimidazole (629 mg, 1.58 mmol) obtained by the step (2e) was mixed with methanol (5 ml) and toluene (15 ml) and the mixture was cooled to −50° C. Then, 3-chloroperbenzoic acid (378 mg, 1.42 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 4 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 obtain the title compound (623 mg, yield: 95.4%) as a colorless foam.

Provenance & Evidence