Hydrochloric Acid → (2S,4S,5S)-5-Amino-6-[4-(2-chlorophenyl)-2,2-dimethyl-5-oxopiperazin-1-yl]-4-hydroxy-2-isopropylhexanoic acid [(S)-2-methylbutyl]amide fumarate

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Reaction Steps

2.3 ml of a solution of 4 N hydrochloric acid in dioxane (9.3 mmol) was added to a solution of 184 mg of {(1S,2S,4S)-1-[4-(2-chlorophenyl)-2,2-dimethyl-5-oxopiperazin-1-ylmethyl]-2-hydroxy-5-methyl-4-[(S)-2-methylbutyl]hexyl}carbamic acid t-butyl ester obtained in Example (2a) (0.31 mmol) in dioxane (0.3 ml) at room temperature, and the mixture was stirred at the same temperature for 15 minutes. A saturated sodium bicarbonate aqueous solution was added to the reaction mixture under cooling in an ice bath, 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/triethylamine=100/10/1). 17.6 mg of fumaric acid (0.24 mmol) was added to a solution of 118 mg of (2S,4S,5S)-5-amino-6-[4-(2-chlorophenyl)-2,2-dimethyl-5-oxopiperazin-1-yl]-4-hydroxy-2-isopropylhexanoic acid [(S)-2-methylbutyl]amide obtained above (0.24 mmol) in methanol (2.4 ml), and the mixture was stirred at room temperature for five minutes. The solvent was evaporated under reduced pressure to obtain 111 mg of the title compound (yield: 59%).

Provenance & Evidence