Methanesulfonic Acid → 5-(Benzoxazol-2-yl)-2-(2-(methylthio)ethyl)-1-(tetrahydropyran-4-yl)benzimidazole

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Reaction Steps

To a solution of 5-(benzoxazol-2-yl)-2-(tetrahydropyran-4-yl)aminoaniline (see Working Example 20-2) (200 mg, 0.646 mmol) in tetrahydrofuran (5 mL) was added 3-(methylthio)propionyl chloride (98.5 mg, 0.711 mmol) and triethylamine (131 mg, 1.29 mmol), and this was stirred at room temperature for 7 hours. After the reaction was complete, water was added and this was extracted with ethyl acetate. After the organic layer obtained was dried over anhydrous sodium sulfate, it was filtered and concentrated. To a solution of the residue obtained in dioxane (5 mL) was added methanesulfonic acid (0.5 mL), and this was heated to reflux for 3 hours. After the reaction was complete, 1M aqueous sodium hydroxide solution was added, and this was extracted with ethyl acetate. The organic layer obtained was dried over anhydrous sodium sulfate, filtered, and concentrated to give crude crystals that were purified by silica gel column chromatography to yield the title compound (170 mg, 67% yield) as colorless crystals.

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