[O:1]=[C:2]1[N:7]([CH2:8][CH2:9][CH2:10][CH2:11][CH2:12][CH2:13][CH2:14][CH2:15][C:16]([O:18]C)=[O:17])[N:6]=[C:5]([C:20]2[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=2)[C:4]([C:26]2[CH:31]=[CH:30][CH:29]=[CH:28][CH:27]=2)=[CH:3]1.[OH-].[Na+]>CO>[O:1]=[C:2]1[N:7]([CH2:8][CH2:9][CH2:10][CH2:11][CH2:12][CH2:13][CH2:14][CH2:15][C:16]([OH:18])=[O:17])[N:6]=[C:5]([C:20]2[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=2)[C:4]([C:26]2[CH:31]=[CH:30][CH:29]=[CH:28][CH:27]=2)=[CH:3]1A mixture of methyl 6-oxo-3,4-diphenyl-1(6H)-pyridazinenonanoate (6 g, 14 mmol), 5N NaOH solution (8.6 mL, 43 mmol) and methanol (100 mL) was heated to reflux on a steam bath. After 30 minutes, the mixture was concentrated, diluted with water and acidified to pH=1 with 2N HCl solution. The mixture was extracted with CH2Cl2, the combined extracts dried over sodium sulfate and concentrated to leave an oil that crystallized on standing. Recrystallization from a mixture of CH2Cl2 and hexanes gave 6-oxo-3,4-diphenyl-1(6H)-pyridazinenonanoic acid (3.92 g, 67%) mp 100°-103° C.
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