Ethanol → 6-(4-Hydroxy-3,5-diisopropyl-phenyl)-hexanoic acid ethyl ester

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Reaction Steps

Boron trifluoride diethyl etherate (4.8 mL, 39 mmol) was added to a mixture of 6-(4-hydroxy-3,5-diisopropyl-phenyl)-6-oxo-hexanoic acid ethyl ester (13.19 g, 39.4 mmol) and ethanedithiol (3.5 mL, 39.3 mmol) in dichloromethane (100 mL), and the resulting deep red mixture was stirred overnight at room temperature. An additional amount of boron trifluoride diethyl etherate (1.2 mL, 10 mmol) was added, and the reaction mixture was stirred an additional 4 hours at room temperature. The reaction mixture was washed with saturated aqueous sodium bicarbonate solution, and the organic solution was dried over magnesium sulfate, filtered, and concentrated to an orange oil. The oil was chromatographed on silica gel (70-230 mesh) using 19:1, then 9:1, then 83:17 hexanes/ethyl acetate, v/v, as eluant. A mixture of this dithioketal (3.65 g, 8.9 mmol), Raney nickel (41 g of a slurry in water), and ethanol (250 mL) is heated to 50° C. for 2.5 hours under nitrogen. No starting material remained by tlc. The ethanol was decanted from the nickel and the nickel washed and decanted twice with ethanol. The combined ethanol solutions were passed through celite, the ethanol evaporated, and the residue chromatographed on silica gel (70 230 mesh) using 4:1, hexanes/ethyl acetate as eluant. The product was obtained as a yellow oil in two portions, 2.95 g. CI Mass Spectrum: [M+H+ ]+ =320.

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