Nitrogen was bubbled through a solution of 8-bromo-1-(2-methylpropyl)-1H-imidazo[4,5-c]-quinolin-4-amine (3.0 g, 9.4 mmol), 4-vinylpyridine (2.0 mL, 19 mmol), triphenylphosphine (246 mg, 0.94 mmol), and triethylamine (2.7 mL, 19 mmol) in acetonitrile (50 mL) for 15 minutes. Palladium (II) acetate (105 mg, 0.47 mmol) was added, and the reaction was heated at 100° C. for three days. The solvent was removed under reduced pressure, and the residue was adjusted to pH 2 with the addition of concentrated hydrochloric acid. Water was added, and the mixture was filtered through a layer of CELITE filter aid. Aqueous sodium carbonate (2 N) was added to the filtrate to adjust the solution to pH 10. The solution was then extracted with dichloromethane, and the combined extracts were dried over sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by flash column chromatography on silica gel (eluting with chloroform:CMA in a gradient from 95:5 to 80:20) to provide 2.1 g of 1-(2-methylpropyl)-8-(2-pyridin-4-ylvinyl)-1H-imidazo[4,5-c]-quinolin-4-amine as a yellow solid.
