[Cl:1][C:2]1[CH:11]=[C:10]2[C:5]([C:6]([OH:15])=[C:7]([N+:12]([O-])=O)[CH:8]=[N:9]2)=[CH:4][CH:3]=1.O.O.[Sn](Cl)Cl.C(O)C.C(=O)(O)[O-].[Na+]>O>[NH2:12][C:7]1[CH:8]=[N:9][C:10]2[C:5]([C:6]=1[OH:15])=[CH:4][CH:3]=[C:2]([Cl:1])[CH:11]=27-Chloro-3-nitro-4-hydroxyquinoline (4.48 g, 20 mmol), tin (II) chloride dihydrate (22.6 g, 100 mmol) and ethanol (200 mL) were combined and then heated at reflux for 4 hours. The reaction mixture was cooled to ambient temperature and then poured into water (250 mL). The mixture was brought to neutral pH by the addition of saturated sodium bicarbonate and then filtered to remove tin salts. The filtrate was extracted with ethyl acetate. The combined organic fractions were dried over magnesium sulfate, filtered and then concentrated under vacuum to provide 1.8 g of 3-amino-7-chloro-4-hydroxyquinoline as a green powder.
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