Trifluoroacetic acid → N-(7-Ethyl-3-(4-isopropylphenyl)-4,6-dimethyl-2,3-dihydro-1-benzofuran-5-yl)-3,3-dimethylbutanamide

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Reaction Steps

To a mixture of N-(7-(1-hydroxyethyl)-3-(4-isopropylphenyl)-4,6-dimethyl-2,3-dihydro-1-benzofuran-5-yl)-3,3-dimethylbutanamide (200 mg, 0.47 mmol) obtained in Example 22 and trifluoroacetic acid (3 mL) was added under ice cooling triethylsilane (0.5 mL, 3.2 mmol) and the resulting mixture was stirred at room temperature for 30 minutes. After the reaction solution was concentrated under reduced pressure, to the residue was added an aqueous saturated sodium hydrogen carbonate solution and the aqueous layer was made alkaline, and the mixture was extracted with ethyl acetate. The organic layer was washed with water and saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane:ethyl acetate=10:1) and recrystallized from hexane to obtain 100 mg (yield: 52%) of the title compound. Melting point: 135-136° C. (ethyl acetate-hexane).

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