2,6-Pyridinedicarboxylic acid → AA 863

Participants

Reaction Steps

In a mixed solvent of acetonitrile (6 ml) and water (3 ml) were dissolved 5-methyl-1,2,3,4-tetramethoxy-6-(12-hydroxy-5,10-dodecadiynyl)benzene (II, 0.50 g, 1.29 mmole) and pyridine-2,6-dicarboxylic acid (0.65 g, 1.29×3 mmole), and the solution was stirred under cooling with ice, followed by adding dropwise and ice-cooled solution of ceric ammonium nitrate (2.12 g) in acetonitrile (4.5 ml) and water (4.5 ml) over a 15-minute period. The reaction was allowed to proceed under the same conditions for 15 minutes and further at room temperature for 15 minutes. After the completion of the reaction, the insolubles were filtered out, and the acetonitrile was distilled off under reduced pressure. By adding isopropyl ether (20 ml) and water (20 ml) to the residue, the product was extracted. The organic layer was washed with aqueous sodium bicarbonate solution and aqueous sodium chloride solution, successively, dried (over MgSO4) and concentrated under reduced pressure, resulting in a residue. The residue was chromatographed on a column of silica gel developing with a mixed solvent of isopropyl ether and ethyl acetate to give 2,3-dimethoxy-5-methyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone (I, 0.42 g, 91%, oil).

Provenance & Evidence