C[O:2][C:3]([C:5]1[CH:6]=[N:7][C:8]2[C:13]([C:14]=1[O:15][CH3:16])=[CH:12][C:11](I)=[CH:10][CH:9]=2)=[O:4].[OH-].[Na+].[C:20](O)(=[O:22])C>CO.O>[CH:20]([C:11]1[CH:12]=[C:13]2[C:8](=[CH:9][CH:10]=1)[N:7]=[CH:6][C:5]([C:3]([OH:2])=[O:4])=[C:14]2[O:15][CH3:16])=[O:22]To the suspension of 6-iodo-4-methoxy-quinoline-3-carboxylic acid methyl ester (example 1d) (5.91 g, 17.2 mmol) in methanol (20 mL) was slowly added the solution of sodium hydroxide (2.76 g, 69 mmol) in water (10 mL). The mixture was stirred at room temperature for 3 hours. The solution was adjusted pH=5.0 using aqueous acetic acid solution. After adding more water, the solid was collected by filtration, washed with water and dried to obtain 6-formyl-4-methoxy-quinoline-3-carboxylic acid. LC-MS m/e 330 (MH+)
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