To a mixture of 2-(4-fluorophenyl)-5-isopropoxy-6-nitrobenzofuran-3-carboxylic acid (1.3 g, 3.62 mmol), tert-butyl (2-aminoethyl)carbamate (0.696 g, 4.34 mmol) in DMF (50 mL) at room temperature was added N,N-diisopropylethylamine (DIPEA) (2.53 mL, 14.47 mmol). The mixture was cooled to 0° C., added with (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) (2.40 g, 5.43 mmol), and then stirred at room temperature (rt) overnight. The reaction mixture was diluted with water, stirred for 5 min. The solid was filtered and dried under suction to obtain the title compound as a yellow solid. Yield: 1.6 g, (88%). 1H NMR (400 MHz, DMSO-d6) δ ppm: 8.61 (t, J=5.65 Hz, 1H) 8.32 (s, 1H) 7.90-8.09 (m, 2H) 7.50 (s, 1H) 7.28-7.46 (m, 2H) 6.91 (t, J=5.65 Hz, 1H) 4.87 (dt, J=12.17, 5.96 Hz, 1H) 3.35-3.49 (m, 2H) 3.06-3.23 (m, 2H) 1.09-1.47 (m, 15H). LCMS: (ES+) m/z=502.34 (M+H)+; Column—ACQUITY UPLC BEH C8 (50×2.1 mm; 1.7 nm); M phase A: 5 mM Ammonium Acetate: MeCN (95:5); M phase B: 5 mM Ammonium Acetate:MeCN (5:95)
