p-Toluenesulfonic acid → 1-Propanone, 1-(2,4-difluorophenyl)-2-[(tetrahydro-2H-pyran-2-YL)oxy]-,(2R)-

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Reaction Steps

2',4'-Difluoro-2-hydroxypropiophenone (61 g) was dissolved in methylene chloride (500 ml), to which was added, under ice-cooling, p-toluene sulfonic acid.hydrate (1.0 g). To the mixture was added, under ice-cooling while stirring, 3,4-dihydro-2H-pyran (41.4 g) during 10 minutes. The mixture was stirred, under ice-cooling, for one hour, to which was added a 5% aqueous solution of sodium hydrogen carbonate (240 ml). The mixture was stirred for 10 minutes under ice-cooling. The methylene chloride layer was separated and dried over anhydrous magnesium sulfate, followed by distilling off the solvent. The residual oily product was purified by means of a silica gel column chromatography (hexane: ethyl acetate=5:1) to afford 2',4'-difluoro-2-(3,4,5,6-tetrahydro-2H-pyran-2-yloxy)propiophenone (86.5 g) as a pale yellow oily product.

Provenance & Evidence