Dimethylformamide → (S)-2-{4'-[(5-acetyl-4-methoxy-3-methyl-benzofuran-2-carbonyl)-amino]-biphenyl-4-sulfonylamino}-3-methyl-butyric acid methyl ester

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Reaction Steps

To 75 mg (0.3 mmol) of 5-acetyl-4-methoxy-3-methyl-benzofuran-2-carboxylic acid was added 1 mL of oxalyl chloride and the mixture was refluxed for 2.5 h in the presence of a catalytic amount of DMF, then the excess oxalyl chloride was removed under vacuum. The residue was dissolved in 1 mL of dichloromethane and was added to a mixture of 163 mg (0.46 mmol) of (S)-2-(4′-amino-biphenyl-4-sulfonylamino)-3-methyl-butyric acid methyl ester and 2 mL of pyridine in an ice/water bath. The mixture was stirred at room temperature overnight. All the solvents were removed under vacuum. Column chromatography on silica gel gave 54 mg (31% yield) of (S)-2-{4′-[(5-acetyl-4-methoxy-3-methyl-benzofuran-2-carbonyl)-amino]-biphenyl-4-sulfonylamino}-3-methyl-butyric acid methyl ester as an off-white solid.

Provenance & Evidence