Reaction Steps
A solution of (S)-4-methyl-2-[4-(2-methyl-benzooxazol-4-yloxy)-2-oxo-2,5-dihydro-pyrrol-1-yl]-pentanoic acid methyl ester (0.570 g, 1.59 mmol) in tetrahydrofuran (10 mL) and water (10 mL) was treated with lithium hydroxide monohydrate (0.134 g 3.12 mmol) and the resulting mixture stirred at room temperature for 1.5 h. The mixture was concentrated in vacuo and the residue treated with acetonitrile, and concentrated in vacuo (repeated 2 additional times). The resulting solid was treated with N,N-dimethylformamide (10 mL) and 1-(3-amino-pyrazol-1-yl)-2-methyl-propan-2-ol (prepared in U.S. Pat. Appl. US2008021032 Example 80, 0.371 g, 2.39 mmol), N,N-diisopropylethylamine (0.820 g, 6.34 mmol) and benzotriazol-1-yl-oxy-tris(dimethylamino)phosphonium hexafluorophosphate (2.811 g, 6.35 mmol) at 0° C. The reaction mixture was allowed to warm to room temperature and stirred for 18 h. The mixture was concentrated in vacuo, the residue dissolved in ethyl acetate, and the resulting solution was washed with aqueous saturated ammonium chloride solution, brine and dried over sodium sulfate. The mixture was filtered and concentrated in vacuo and the residue purified by ISCO flash column chromatography (Silicycle 40 g, 5% to 100% ethyl acetate/hexanes) which afforded (S)-4-methyl-2-[4-(2-methyl-benzooxazol-4-yloxy)-2-oxo-2,5-dihydro-pyrrol-1-yl]-pentanoic acid [1-(2-hydroxy-2-methyl-propyl)-1H-pyrazol-3-yl]-amide (400 mg, 52%) as a light yellow solid: HR-ES-MS m/z calculated for C25H31N5O5 [M+H]+ 482.2398, observed 482.2398; 1H NMR (300 MHz, DMSO-d6) δ ppm 0.90 (d, J=6.0 Hz, 3H), 0.94 (d, J=6.0 Hz, 3H), 1.05 (br. s., 3H), 1.06 (br. s., 3H), 1.37-1.64 (m, 2H), 1.65-1.85 (m, 1H), 2.62 (s, 3H), 3.89 (s, 2H), 4.24 (d, J=18.1 Hz, 1H), 4.62 (d, J=18.1 Hz, 1H), 4.67 (s, 1H), 4.83 (s, 1H), 4.89 (dd, J=11.0, 3.8 Hz, 1H), 6.45 (s, 1H), 7.29 (d, J=7.8 Hz, 1H), 7.42 (t, J=7.8 Hz, 1H), 7.54 (s, 1H), 7.64 (d, J=7.8 Hz, 1H), 10.80 (s, 1H).
