Trifluoroacetic acid → (2S,4S,5S)-5-Amino-6-[2,2-dimethyl-4-(5-fluoro-2-methylphenyl)-5-oxopiperazin-1-yl]-4-hydroxy-2-isopropylhexanoic acid isobutylamide hemifumarate

Participants

Reaction Steps

0.95 ml of trifluoroacetic acid (12.33 mmol) was added to a solution of 238 mg of {(1S,2S,4S)-4-isobutylcarbamoyl-1-[4-(5-fluoro-2-methylphenyl)-2,2-dimethyl-5-oxopiperazin-1-ylmethyl]-2-hydroxy-5-methylhexyl}carbamic acid t-butyl ester obtained in Example (71a) (0.411 mmol) in methylene chloride (2 ml) at room temperature, and the mixture was stirred at the same temperature for 30 minutes. The reaction mixture was concentrated under reduced pressure and diluted with a saturated sodium bicarbonate aqueous solution, 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=20/1-10/1). 20.8 mg of fumaric acid (0.179 mmol) was added to a solution of 172 mg of (2S,4S,5S)-5-amino-6-[2,2-dimethyl-4-(5-fluoro-2-methylphenyl)-5-oxopiperazin-1-yl]-4-hydroxy-2-isopropylhexanoic acid isobutylamide obtained above (0.35 mmol) in methanol (2 ml), and the mixture was stirred at room temperature for five minutes. The solvent was evaporated under reduced pressure to obtain 152 mg of the title compound (yield: 80%).

Provenance & Evidence