Trifluoroacetic acid → 5,5-Dimethyl-1-(5-fluoro-2-methylphenyl)piperazin-2-one

Participants

Reaction Steps

10 ml of trifluoroacetic acid (134 mmol) was added to a solution of 4.5 g of 2,2-dimethyl-4-(5-fluoro-2-methylphenyl)-5-oxopiperazine-1-carboxylic acid t-butyl ester obtained in Example (70c) (13.4 mmol) in methylene chloride (20 ml) at room temperature, and the mixture was stirred at the same temperature for 30 minutes. The reaction mixture was concentrated under reduced pressure. A saturated sodium bicarbonate aqueous solution was added, followed by extraction with methylene chloride. Then, the organic layer was dried over anhydrous magnesium sulfate. After filtration, the solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography (elution solvent:methylene chloride/methanol=10/1) to obtain 2.71 g of the title compound (yield: 86%).

Provenance & Evidence