[OH:1][C:2]1[CH:3]=[N:4][C:5]2[C:10]([C:11]=1[C:12]([O:14][CH3:15])=[O:13])=[CH:9][CH:8]=[CH:7][CH:6]=2.[C:16](=O)([O-])[O-].[K+].[K+].CI>CC(C)=O.O>[CH3:16][O:1][C:2]1[CH:3]=[N:4][C:5]2[C:10]([C:11]=1[C:12]([O:14][CH3:15])=[O:13])=[CH:9][CH:8]=[CH:7][CH:6]=2Methyl 3-hydroxycinchoninate, (J. Org. Chem. 1953, 18, 552) (1.53 g, 7.54 mmol), potassium carbonate (1.15 g, 8.29 mmol) in acetone (11 ml) was treated with methyl iodide (470 uL, 7.54 mmol) was stirred at RT under nitrogen overnight. The mixture diluted with water and extracted into DCM and washed with satd. sodium thiosulfate solution. The organics were dried over Na2SO4 and concentrated. Material purified by SGC (Combi flash, 10-50% EtOAc-hexanes over 40 minutes) gave methyl 3-methoxycinchoninate. 1H NMR (CDCl3) δ 8.85 (s, 1H), 8.07 (d, 1H), 7.72 (d, 1H), 7.61 (m, 2H), 4.08 (s, 3H), 4.03 (s, 1H). MS (ESI+) for m/z 218 (M+H)+.
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