Hydrochloric Acid → 7-Fluoro-5-methyl-6-phenyl-2-(piperidin-1-ylcarbonyl)-1,3-benzoxazole-4-carbonitrile

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Reaction Steps

Under nitrogen atmosphere, trimethylaluminium (1.03 M n-hexane solution, 898 μl, 925 μmol) was dropwise added to a dichloromethane (1 ml) solution of piperidine (92 μl, 925 μmol) at room temperature, and stirred for 15 minutes. Subsequently, a dichloromethane (2 ml) solution of ethyl 4-cyano-7-fluoro-5-methyl-6-phenyl-1,3-benzoxazole-2-carboxylate (I-111) (150 mg, 463 μl) was dropwise added and stirred for 63 hours. After the reaction, aqueous 1 N hydrochloric acid solution was added to the reaction liquid with cooling with ice, followed by stirring at room temperature. The reaction liquid was extracted with chloroform. Next, the obtained organic layers were combined, dried over anhydrous magnesium sulfate, filtered, and the filtrate was concentrated under reduced pressure. The resulting residue was subjected to silica gel column chromatography, and the eluate with n-hexane/ethyl acetate (4:1, v/v) gave the entitled compound (62 mg, 37%) as a white solid.

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