COC1C=CC(C[NH:8][C:9]2[C:18]3[C:13](=[CH:14][CH:15]=[CH:16][CH:17]=3)[NH:12][C:11](=[O:19])[C:10]=2[C:20]([O:22][CH3:23])=[O:21])=CC=1>C(O)(C(F)(F)F)=O>[NH2:8][C:9]1[C:18]2[C:13](=[CH:14][CH:15]=[CH:16][CH:17]=2)[NH:12][C:11](=[O:19])[C:10]=1[C:20]([O:22][CH3:23])=[O:21]Methyl 4-(4-methoxybenzylamino)-2-oxo-1,2-dihydroquinoline-3-carboxylate (Example 68a) (0.841 g, 2.49 mmol) was dissolved in TFA (5 mL) and stirred at room temperature for 30 minutes. The TFA was removed under reduced pressure, and the residue was dissolved in dichloromethane, then precipitated out by adding excess diethyl ether. The resultant solid was collected by filtration, suspended in dichloromethane, and washed with concentrated sodium bicarbonate. The solid was collected to give methyl 4-amino-2-oxo-1,2-dihydroquinoline-3-carboxylate (0.230 g, 42%) as a white solid. M.p.: 236° C. 1H NMR (400 MHz, DMSO-d6) δ 3.73 (s, 3H), 7.12 (t, J=8.0 Hz, 1H), 7.17 (d, J=8.0 Hz, 1H), 7.52 (t, J=8.0 Hz, 1H), 8.08 (d, J=8.0 Hz, 1H), 8.38 (bs, 2H), 10.88 (bs, 1H). MS 219 (MH+).
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