Ammonium Chloride → (S)-6-(5-fluoro-2-methylphenyl)-6-methyl-4-trifluoromethylhept-1-yn-4-ol

Participants

Reaction Steps

To a solution of (R)-2-[2-(5-fluoro-2-methylphenyl)-2-methylpropyl]-2-trifluoromethyloxirane (18.5 g, 67.0 mmol) in 200 mL of anhydrous DMSO was added lithium trimethylsilylacetylide (0.5 M in THF, 201 mL, 101 mmol). The resulting brown solution was stirred at room temperature for 5 hours. The reaction mixture was poured into 500 mL of water and extracted with three 500 mL portions of 10% ethyl acetate/hexanes. The combined organic phases were washed with two 500 mL portions of water and one 500 mL portion of brine, dried over magnesium sulfate, filtered, and concentrated in vacuo. The crude material was redissolved in 200 mL of THF and cooled to 0° C. A solution of tetrabutylammonium fluoride (1.0 M in THF, 67.0 mL, 67.0 mmol) was added over 5 minutes. The reaction mixture was stirred for 1 hour, poured into 150 mL of saturated aqueous ammonium chloride solution, and extracted with three 300 mL portions of diethyl ether. The combined organic phases were washed with 300 mL of brine, dried over magnesium sulfate, filtered, and concentrated in vacuo. Purification by column chromatography with silica gel (eluted with 0%-3% EtOAc/hexanes) afforded (S)-6-(5-fluoro-2-methylphenyl)-6-methyl-4-trifluoromethylhept-1-yn-4-ol as a yellow oil (13.2 g, 65%).

Provenance & Evidence