Ammonium Chloride → 2',4'-Difluoro-2-methyl-3-(4-cyanophenyl)-propiophenone

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Reaction Steps

A 19 g portion of 2,4-difluoropropiophenone was dissolved in 150 ml of tetrahydrofuran. With cooling in a dry ice-acetone bath and spending 20 minutes or more, to this was added dropwise 112 ml of 1N tetrahydrofuran solution of lithium hexamethyl disilazide. After 1 hour of stirring at the same temperature, to this was further added dropwise 50 ml of tetrahydrofuran solution containing 14 g of 4-cyanobenzyl bromide spending 20 minutes or more, followed by overnight stirring at room temperature. The reaction solution was mixed with saturated ammonium chloride aqueous solution, poured into water and then extracted with ethyl acetate. The thus obtained organic layer was washed with water and dried on anhydrous magnesium sulfate. After removing the solvent by evaporation under a reduced pressure, the resulting residue was purified by a silica gel column chromatography (ethyl acetate:n-hexane=1:9) to obtain 13 g of 2',4'-difluoro-2-methyl-3-(4-cyanophenyl)-propiophenone with a yield of 41%.

Provenance & Evidence