3-Amino-5-chloro-2-hydroxybenzenesulfonic acid → (2S)-2-amino-4-[(5-chloro-2-hydroxy-3-sulfophenyl)carbamoyl]butanoic acid

Participants

Reaction Conditions

Reaction Steps

Boc-Glu-OtBu (100 mg, 0.33 mmol) and HOBt monohydrate (65.6 mg, 0.43 mmol) were dissolved in 2 ml of DMF, and triethylamine (0.137 ml) was added to the solution. After cooling to 0° C., diisopropylcarbodiimide (66.4 μl, 0.43 mmol) and 2-amino-4-chlorophenol-6-sulfonic acid (73.7 mg, 0.33 mmol) were added, followed by stirring at room temperature overnight. After the solvent was removed by distillation, the mixture was purified according to the purification step A. The resulting intermediate was dissolved in 2 ml of TFA. The solution was stirred at room temperature for 2 hours, and 2 ml of methylene chloride was added thereto. The precipitate was taken out by filtration to give the title compound.

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