Benzofuran-2-carboxylic acid → Benzofuran-2-carboxylic acid 4'-(1-tert-butoxycarbonyl-2-methyl-propylsulfamoyl)-biphenyl-4-yl ester

Beteiligte Stoffe

Reaktionsschritte

To benzofuran-2-carboxylic acid (0.401 g, 2.47 mmol, 1 equiv.) dissolved in dry dichloromethane (50 mL) was added dicyclohexylcarbidiimide (1.019 g, 4.94 mmol, 2 equiv) and the mixture was stirred under nitrogen for 15 minutes. Then 2-(4′-hydroxy-biphenyl-4-sulfonylamino)-3-methyl-butyric acid tert-butyl ester (1.0 g, 2.47 mmol, 1 equiv., Example 134, Step 1) was introduced to the reaction mixture, followed by the addition of 4-dimethylamino pyridine (0.050 g, 0.41 mmol). The mixture was allowed to stir at room temperature overnight. The reaction mixture was then diluted with dichloromethane, washed with water and brine. The organic layer was dried over magnesium sulfate and the solvent was concentrated in vacuo. The residue was dissolved in ethyl acetate and purified by column chromatography on silica gel eluting with 20% ethyl acetate/hexane to afford 325 mg of benzofuran-2-carboxylic acid 4′-(1-tert-butoxycarbonyl-2-methyl-propylsulfamoyl)-biphenyl-4-yl ester in 31% yield. 1H NMR (400 MHz, CDCl3) δ ppm 0.87 (d, J=6.82 Hz, 3 H) 1.03 (d, J=6.82 Hz, 3 H) 1.21 (s, 9 H) 2.07 (m, 1 H) 3.68 (dd, J=9.85, 4.55 Hz, 1 H) 5.15 (d, J=9.85 Hz, 1 H) 7.37 (m, 3 H) 7.53 (t, J=7.83 Hz, 1 H) 7.66 (m, 5 H) 7.77 (m, 2 H) 7.92 (d, J=8.34 Hz, 2 H).

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