Tetrabutylammonium Fluoride → Ethyl-4-(2-methoxyphenyl)-2-hydroxy-4-methyl-2-(pentafluoroethyl)-pentanoate

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Reaction Steps

Analogously to Example 7, 687 mg of ethyl-4-(2-methoxyphenyl)-4-methyl-2-oxopentanoate (WO 00/32584) with 1 g of (pentafluoroethyl)trimethylsilane and 0.5 ml of (tetrabutylammonium fluoride solution (1 M in THF)) in 18 ml THF are reacted to form g of ethyl-4-(2-methoxyphenyl)-2-hydroxy-4-methyl-2-(pentafluoroethyl)-pentanoate. 450 mg of the ester that is obtained in 12 ml of diethyl ether is mixed in portions at 0° C. with 66 mg of lithium aluminum hydride. After stirring for 11 hours, it is added to saturated bicarbonate solution and filtered through diatomaceous earth. The phases are separated, and the aqueous phase is extracted with ethyl acetate. The organic phase is washed with water and brine, dried (Na2SO4) and concentrated by evaporation. 420 mg of diol is obtained as a yellow oil. 400 mg of the diol is oxidized to the corresponding aldehyde with 0.11 ml of oxalyl chloride, 0.21 ml of DMSO and 1 ml of triethylamine. It is washed with water and brine, dried with sodium sulfate, and concentrated by evaporation in a vacuum. After chromatography on silica gel (hexane/ethyl acetate 0→5%), 268 mg of the title compound is obtained as a yellow oil.

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