[Br:1][C:2]1[CH:7]=[C:6]([C:8]([OH:10])=[O:9])[CH:5]=[CH:4][N:3]=1.[C:11]1(C)C=CC=C[CH:12]=1.S(=O)(=O)(O)O.C(=O)(O)[O-].[Na+]>C(O)C>[CH2:11]([O:9][C:8]([C:6]1[CH:5]=[CH:4][N:3]=[C:2]([Br:1])[CH:7]=1)=[O:10])[CH3:12]To a suspension of 2-bromo4-pyridine carboxylic acid (prepared according to the method of Ashimori, Chem. Pharm. Bull. 38 (9) 2446-2458 (1990)) in 2:1 toluene: absolute ethanol (45 mL) was added sulfuric acid (0.75 mL). The mixture was heated at reflux for 16 h. The mixture was poured into saturated aqueous sodium bicarbonate and extracted with chloroform (3 times). The combined chloroform extracts were dried over magnesium sulfate, filtered and concentrated afforded the crude product as a yellow oil. Purification by silica gel chromatography eluting with 9:1 hexane:ethyl acetate to afford the title compound (900 mg) as a clear, colorless oil.
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