Cyanomethylenetributylphosphorane → t-Butyl 4-[(4-chlorophenyl)sulfonyl]-4-(2,5-difluorophenyl)-1-piperidinecarboxylate

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Reaction Steps

The t-butyl N-[3-[(4-chlorophenyl)sulfonyl]-3-(2,5-difluorophenyl)propyl]-N-(2-hydroxyethyl)carbamate (200 mg, 0.404 mmol) obtained in Example 257 was dissolved in toluene (10 ml), followed by the addition of cyanomethylenetri-n-butylphosphorane (200 mg, 0.829 mmol). Under an argon atmosphere, the resulting mixture was heated under reflux for 8 hours. After the reaction mixture was allowed to cool down, cyanomethylenetri-n-butylphosphorane (200 mg, 0.829 mmol) was added thereto. Under an argon atmosphere, the mixture was heated under reflux for 14 hours. After the reaction mixture was allowed to cool down, the residue obtained by concentrating the reaction mixture under reduced pressure was subjected to flash silica gel chromatography, and the fraction obtained from the hexane:ethyl acetate=4:1 eluate was concentrated under reduced pressure to give a white solid. The white solid was washed with diethyl ether, whereby the title compound (140 mg, 0.297 mmol, 74%) was obtained as a white powder.

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