C[O:2][C:3](=[O:13])[C:4]1[CH:9]=[C:8]([Cl:10])[N:7]=[C:6]([Br:11])[C:5]=1[NH2:12].[OH-].[Na+].C(OCC)C.O>CO>[NH2:12][C:5]1[C:6]([Br:11])=[N:7][C:8]([Cl:10])=[CH:9][C:4]=1[C:3]([OH:13])=[O:2]3-Amino-2-bromo-6-chloroisonicotinic acid methyl ester (260 mg) (example 3, step 5) was dissolved in methanol (2 mL), 2N aqueous sodium hydroxide solution (2 mL) was added and the reaction mixture was stirred for 2 hours at reflux. After cooling to room temperature, diethyl ether and water were added and the layers were separated. The aqueous layer was washed with diethyl ether and acidified by addition of 2N hydrochloric acid. The formed precipitate was extracted with MTB-ether (3×), the combined organic layer was washed with brine, dried over MgSO4 and concentrated in vacuum to afford 246 mg of
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