Diisopropylethylamine → (S)-3-methyl-2-{4'-[(5-chloro-benzothiazole-2-carbonyl)-amino]-biphenyl-4-sulfonylamino}-butyric acid tert-butyl ester

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Reaction Steps

To 5-chloro-benzothiazole-2-carboxylic acid sodium salt (150 mg, 0.64 mmol) was added (S)-2-(4′-amino-biphenyl-4-sulfonylamino)-3-methyl-butyric acid tert-butyl ester (310 mg, 1.2 eq), BOP (340 mg, 1.2 eq), N,N-diisopropylethylamine (99 mg, 1.2 eq) and 4 mL of DMF. The mixture was stirred at room temperature overnight. The reaction mixture was poured into brine, and extracted with ethyl acetate. The combined organic solution was washed with brine and water. Removal of solvent gave the crude product, which was purified by column chromatography on silica gel to give 136 mg of (S)-3-methyl-2-{4′-[(5-chloro-benzothiazole-2-carbonyl)-amino]-biphenyl-4-sulfonylamino}-butyric acid tert-butyl ester was obtained as a white solid.

Provenance & Evidence