Reaction Steps
Tris(dibenzylideneacetone)dipalladium(0) chloroform adduct (0.095 g, 0.03 eq.), 3-iodopyridine (0.626 g, 1.1 eq.), triethylamine (0.923 g, 3 eq.), and copper (I) iodide (0.035 g, 0.06 eq.) were added sequentially to a solution of 2-ethyl-1-(4-pentynyl) 1H-imidazo[4,5-c]quinolin-4-amine (0.85 g, 3.0 mmol, 1.0 eq.) in DMF. The reaction mixture was stirred for 1 hour and then concentrated under reduced pressure. The residue was purified by column chromatography (silica gel eluting with 4/96 methanol/dichloromethane). The product was recrystallized from a mixture of ethanol and 1,2-dichloroethane. The resulting solid was dissolved in 1:1 mixture of ethanol and 1,2-dichloroethane, treated with activated charcoal, combined with a few drops of 10% sodium hydroxide, heated and then filtered while still hot. The filtrate was concentrated under reduced pressure to provide 0.2 g of 2-ethyl-1-[5-(pyridin-2-yl)-4-pentynyl]-1H-imidazo[4,5-c]quinolin-4-amine as light brown granules, mp 188.0-192.0° C. 1H NMR (300 MHz, CDCl3) δ 8.70 (d, J=0.9 Hz, 1H), 8.55 (dd, J=4.7, 1.3 Hz, 1H), 8.06 (dd, J=8.2, 0.9 Hz, 1H), 7.82 (dd, J=8.4, 0.7 Hz, 1H), 7.71 (ddd, J=7.9, 1.7, 1.7 Hz, 1H), 7.48 (ddd, J=8.3, 7.2, 1.2 Hz, 1H), 7.25 (m, 2H), 5.46 (br s, 2H), 4.66 (t, J=7.9 Hz, 2H), 3.00 (q, J=7.4 Hz, 2H), 2.64 (t, J=6.5 Hz, 2H), 2.26 (m, 2H), 1.49 (t, J=7.4 Hz, 3H); MS (APCI) m/z 356 (M+H)+; Anal. calcd for C22H21N5.0.65H2O: C, 71.97; H, 6.12; N, 19.07. Found: C, 72.03; H, 6.06; N, 19.16.
