In a dried sealable pressure tube flushed with nitrogen was placed methyl 5-bromo-8-{[(4-methylphenyl)sulfonyl]oxy}-1,6-naphthyridine-7-carboxylate (500 mg, 1.14 mmol, prepared as described in Example 2, Step 2), N-methylmethanesulfonamide (168 mg, 1.54 mmol, prepared as in J. Chem. Soc., Perkins Trans. 1986, 2 (8): 1211-16), 2,2′-bipyridyl (241 mg, 1.54 mmol), dry DMF (3 mL) and copper(I) oxide (221 mg, 1.54 mmol). The tube was capped and heated to 85° C. overnight. In the morning, the reaction was cooled and filtered through a glass fiber filter, washing with chloroform. The filtrate was diluted with chloroform (about 100 mL total volume) and stirred with an EDTA solution (5 g EDTA in 100 mL water) for two hours or until the aqueous layer became aqua in color and the organic layer became yellow. The layers were separated and the aqueous layer was extracted twice more with chloroform. The combined organic extracts were dried over sodium sulfate, filtered, and concentrated in vacuo. The residue was purified by flash column chromatography (ISCO column, 110 g silica) eluting with a 0-5% MeOH/CHCl3 gradient over 35 minutes. The concentrated fractions were triturated with methanol to give the product as a white solid.
