Hexane → (3R)-2-(2,4-Difluorophenyl)-3-(3,4,5,6-tetrahydro-2H-pyran-2-yloxy)-1-butene

Participants

Reaction Conditions

Reaction Steps

A mechanically stirred mixture of methyl triphenylphosphonium bromide (84.6 g, 0.237 moles) in 175 ml of dry tetrahydrofuran was cooled to 8° C. A solution of lithium bis (trimethylsilyl)amide (42.4 g, 0.253 moles) in 250 ml tetrahydrofuran was added to the above mixture at a rate so that the temperature of the mixture remained 23° C. After stirring for 1 hour at room temperature the contents were cooled to -70° C. and stirred for 1/2 hour. Added a solution of compound 4b, (2R)-2',4'-Difluoro-2-(3,4,5,6-tetrahydro-2H-pyran-2-yloxy)propiophenone (50 g, 0.185 moles) in 125 ml of tetrahydrofuran slowly to maintain the temperature of the mixture below -70° C. The resulting mixture was stirred at 7° C. for 60 hours. Added 33 ml of ethyl acetate to the above mixture followed by the addition of 2 L of hexane and allowed to stand for 15 minutes. The solid was removed by suction-filtration and washed thoroughly with 325 ml of hexane. The filtrate was washed with 1:1 mixture of methanol : water (2×650 ml) and brine (650 ml) and dried over MgSO4. The solvent was evaporated to give the title compound 5b as an oil (47.7 g, 96%).

Provenance & Evidence