Hydrochloric Acid → 5-[4-(4-Ethoxy2,3-difluorophenoxymethyl)cyclohexyl]tetrahydropyran-2-one

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Reaction Steps

In a reactor under nitrogen atmosphere, 20 mL of ethanol and 0.4 g of sodium cyanoborohydride were added to 5.4 g of ethyl 4-[4-(4-ethoxy-2,3-difluorophenoxymethyl)cyclohexyl]5-oxopentanoate obtained in the eleventh step, and pH of the mixture was adjusted to about 3 with hydrochloric acid (2M), followed by stirring at room temperature for 15 hours. 30 mL of water was added to the reaction solution, which was extracted three times with 20 mL of toluene. The mixture including the organic layer was washed with water and dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was placed in a flask equipped with a Dean-Stark apparatus, to which 100 mL of toluene and 0.1 g of p-toluenesulfonic acid monohydrate were added, and the mixture was refluxed for 1 hour while the solvent was distilled off with the Dean-Stark apparatus. The solution was cooled to room temperature, washed with water, and dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography to provide 4.5 g of 5-[4-(4-ethoxy2,3-difluorophenoxymethyl)cyclohexyl]tetrahydropyran-2-one.

Provenance & Evidence