To a solution of ethyl 4-amino-5-(3-(isopropylamino)-2,2-dimethyl-3-oxopropoxy)-2-methylquinoline-3-carboxylate (Example 134a, 14.0 g, 36.2 mmol) in EtOH (140 mL) was added aqueous NaOH solution (2.0 N, 46 mL) at room temperature. The reaction mixture was stirred at 90° C. for 4 hrs. The resulting solution was neutralized at 0° C. to pH 7 with 6 N HCl, and concentrated under reduced pressure. The residue was re-dissolved in EtOH (400 mL) and water (25 mL), and treated with charcoal (200 mg) at 65° C. for 30 minutes. After removal of the charcoal by filtration, the filtrate was concentrated, and the resultant white solid was purified by re-crystallization from EtOH/H2O and dried under vacuum at 70° C. to give the title compound as a white solid (11.5 g, 89%). M.p.: 216-218° C. 1H NMR (400 MHz, DMSO-d6) δ 1.01 (d, J=6.4 Hz, 6H), 1.24 (s, 6H), 2.75 (s, 3H), 3.86-3.93 (m, 1H), 4.17 (s, 2H), 7.01 (d, J=8.0 Hz, 1H), 7.28 (d, J=8.4 Hz, 1H), 7.57 (d, J=7.6 Hz, 1H), 7.67 (t, J=8.0 Hz, 1H), 8.83 (brs, 1H), 12.34 (brs, 1H), 12.78 (brs, 1H). MS 360 (MH+).
