[CH3:1][O:2][CH2:3][CH2:4][O:5][C:6]1[C:15]([CH3:16])=[C:14]2[C:9]([CH:10]=[CH:11][C:12]([CH3:17])=[N:13]2)=[CH:8][CH:7]=1.[Se](=O)=[O:19]>O1CCOCC1.O>[CH3:1][O:2][CH2:3][CH2:4][O:5][C:6]1[C:15]([CH3:16])=[C:14]2[C:9]([CH:10]=[CH:11][C:12]([CH:17]=[O:19])=[N:13]2)=[CH:8][CH:7]=1To 7-(2-methoxyethoxy)-2,8-dimethylquinoline (90 mg, 0.39 mmol) in dioxane/water (5 mL/0.5 mL) at ambient temperature was added selenium dioxide (52 mg, 0.47 mmol) and the reaction was heated to reflux for 1 hour. After cooling, the reaction was filtered and the solids washed with DCM. The filtrate was dried over MgSO4, filtered and concentrated under reduced pressure. The residue was purified by reverse phase chromatography (SP4, 12M, eluting with a gradient of water/ACN 100:0 to 0:100, 20 column volumes) to yield 7-(2-methoxyethoxy)-8-methylquinoline-2-carbaldehyde (67 mg, 70% yield) as a tan solid.
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