[CH2:1]([O:3][C:4]([N:6]1[C:15]2[C:10](=[CH:11][C:12]([O:18][CH3:19])=[C:13]([O:16][CH3:17])[CH:14]=2)[C:9](=O)[CH2:8][CH:7]1[CH3:21])=[O:5])[CH3:2].Cl.[NH2:23][OH:24].C([O-])(=O)C.[Na+].O>C(O)C>[CH2:1]([O:3][C:4]([N:6]1[C:15]2[C:10](=[CH:11][C:12]([O:18][CH3:19])=[C:13]([O:16][CH3:17])[CH:14]=2)[C:9](=[N:23][OH:24])[CH2:8][CH:7]1[CH3:21])=[O:5])[CH3:2]
A stirred solution of 6,7-dimethoxy-2-methyl-4-oxo-3,4-dihydro-2H-quinoline-1-carboxylic acid ethyl ester (10.0 g, 34.1 mmol), hydroxylamine hydrochloride (7.1 g, 102 mmol), and sodium acetate (7.0 g, 85 mmol) in ethanol (50 mL) was heated at reflux for 2 h. Water (50 mL) was added, and the volatiles were removed in vacuo. Ethyl acetate (175 mL) was added, and the mixture was stirred vigorously for 10 min. The aqueous phase was separated and extracted with ethyl acetate (2×60 mL). The combined organic layers were washed with brine (25 mL), dried over magnesium sulfate, filtered and concentrated in vacuo to give the title compound as a white foam (12.28 g, ca. 100%). 1H NMR (CDCl3) δ 1.1 (d, 3H), 1.32 (t, 3H), 2.77 (dd, 1H), 3.07 (dd, 1H), 3.89 (s, 6H), 4.2-4.4 (m, 2H), 5.0 (m, 1H), 7.18 (s, 1H), 7.26 (s, 1H).
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