(Diethylamino)sulfur trifluoride → Ethyl cis(+/-)-2-(4-{[(4-chloro-5-ethyl-1H-imidazol-2-yl)carbonyl]amino}-3-methoxypiperidin-1-yl)-4-(fluoromethyl)-1,3-thiazole-5-carboxylate

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Reaction Steps

Ethyl cis(±)-2-(4-{[(4-chloro-5-ethyl-1H-imidazol-2-yl)carbonyl]amino}-3-methoxypiperidin-1-yl)-4-(hydroxymethyl)-1,3-thiazole-5-carboxylate obtained by the method described in Example (27b) (0.14 g, 0.30 mmol) was dissolved in dichloromethane (5 mL). A solution of DAST (0.05 mL, 0.38 mmol) in dichloromethane (2 mL) was added dropwise at −40° C. The mixture was stirred at that temperature for 30 minutes. Brine was added to the reaction solution, followed by extraction with dichloromethane. The organic layer was washed with brine and dried over anhydrous sodium sulfate. Following concentration under reduced pressure, the residue was purified by silica gel column chromatography (elution solvent: hexane/ethyl acetate=4/1, 3/1, 1/1) to obtain 83 mg of the title compound as a colorless oily substance (59%).

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