Reaction Steps
To a solution of (S)-2-[4-(benzooxazol-4-yloxy)-2-oxo-2,5-dihydro-pyrrol-1-yl]-4-methyl-pentanoic acid methyl ester (0.140 g, 0.41 mmol) in tetrahydrofuran (10 mL) and water (10 mL) was added lithium hydroxide monohydrate (0.033 g 0.77 mmol). The mixture was stirred at room temperature for 1.25 h and then partitioned between ethyl acetate and water. The aqueous phase was acidified with 1N aqueous hydrochloric acid (pH<2), and extracted with ethyl acetate. The combined organic layers were dried over magnesium sulfate, filtered and concentrated in vacuo. The resulting residue was treated with acetonitrile, dichloromethane/hexanes which formed a yellow precipitate. The precipitate was isolated by filtration and dissolved in N,N-dimethylformamide (2 mL). This mixture was treated with 1-(3-amino-pyrazol-1-yl)-2-methyl-propan-2-ol (prepared in U.S. Pat. Appl. US2008021032 Example 80, 0.021 g, 0.14 mmol), N,N-diisopropylethylamine (0.035 g, 0.27 mmol) and benzotriazol-1-yl-oxy-tris(dimethylamino)phosphonium hexafluorophosphate (0.060 g, 0.14 mmol) at 0° C. The reaction mixture was then warmed up to room temperature and stirred for 18 h. The mixture was concentrated in vacuo and the resulting residue was dissolved in ethyl acetate. The ethyl acetate layer was washed with aqueous saturated ammonium chloride and brine, and dried over sodium sulfate, filtered and concentrated in vacuo. The residue was purified by reverse phase HPLC (C18, 20×150 mm column, 40% to 100% acetonitrile/water gradient) which afforded (S)-2-[4-(2-amino-3-hydroxy-phenoxy)-2-oxo-2,5-dihydro-pyrrol-1-yl]-4-methyl-pentanoic acid [1-(2-hydroxy-2-methyl-propyl)-1H-pyrazol-3-yl]-amide (0.007 g, 16%) as a yellow solid: HR-ES-MS m/z calculated for C23H31N5O5 [M+H]+ 458.2398, observed 458.2397; 1H NMR (300 MHz, DMSO-d6) δ ppm 0.88 (d, J=6.0 Hz, 3H), 0.92 (d, J=6.0 Hz, 3H), 1.03 (br. s., 3H), 1.04 (br. s., 3H), 1.38-1.60 (m, 2H), 1.62-1.80 (m, 1H), 3.87 (s, 2H), 4.18 (d, J=17.8 Hz, 1H), 4.47-4.60 (m, 3H), 4.62 (s, 1H), 4.66 (s, 1H), 4.87 (dd, J=10.6, 4.5 Hz, 1H), 6.38-6.45 (m, 2H), 6.54 (dd, J=8.2, 1.0 Hz, 1H), 6.59 (dd, J=7.5, 1.0 Hz, 1H), 7.52 (d, J=2.1 Hz, 1H), 9.47 (s, 1H), 10.75 (s, 1H).
