[CH:1]([N:4]1[C:9]([CH3:10])=[C:8]([CH3:11])[CH:7]=C(C#N)[C:5]1=[O:14])([CH3:3])[CH3:2].[OH-:15].[K+].[CH2:17]([OH:19])[CH3:18]>O>[CH:1]([N:4]1[C:9]([CH3:10])=[C:8]([CH3:11])[CH:7]=[C:18]([C:17]([OH:15])=[O:19])[C:5]1=[O:14])([CH3:3])[CH3:2]A mixture of 1-isopropyl-5,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile as prepared in 3(1) (840 mg, 4.42 mmol), potassium hydroxide (1.84 g, 32.7 mmol), ethanol (12 mL) and water (3 mL) was refluxed for 16 h. After cooling, the mixture was concentrated in vacuo. The aqueous residue was diluted with water (80 mL), washed with ethyl acetate (80 mL), and acidified with 2N hydrochloric acid aqueous solution (pH˜5) at 0° C. The aqueous suspension was extracted with dichloromethane (50 mL×3). The combined organic layers were dried over magnesium sulfate and concentrated in vacuo to give 838 mg (91%) of the title compound as a white solid.
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