Hydrochloric Acid → Cyclohexyl(5-fluoro-3-methyl-1-benzofuran-2-yl)methanol

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Reaction Steps

To a solution (80 mL) of 5-fluoro-N-methoxy-N,3-dimethyl-1-benzofuran-2-carboxamide (4.37 g) synthesized above in tetrahydrofuran was added dropwise 1.5M diisobutylaluminum hydride toluene solution (24.5 mL) at 0° C., and the mixture was stirred for 1 hr. 1N Hydrochloric acid was added to quench the reaction, and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate:hexane=1:9, volume ratio) to give a pale-brown solid. To a solution (50 mL) of the obtained solid in tetrahydrofuran was added dropwise 1.0M cyclohexylmagnesium bromide tetrahydrofuran solution (21.8 mL) at 0° C., and the mixture was stirred for 1 hr. Saturated aqueous ammonium chloride solution was added to quench the reaction, and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate:hexane=3:17, volume ratio) to give the title object compound (1.32 g, 27%) as a pale-yellow oil.

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