Reaction Steps
A solution of N1-(3-aminopropyl)-2-ethoxymethyl-1H-imidazo[4,5-c]quinoline-1,4-diamine (1.04 g, 3.31 mmol) in 30 mL of CH2Cl2 and 5 mL of N,N-dimethylformamide was placed under an atmosphere of nitrogen and slowly treated with isopropyl isocyanate (0.320 mL, 3.31 mmol). After 15 h, the reaction mixture was concentrated under reduced pressure to yield a yellow/orange foam. The foam was purified by chromatography (SiO2, 30% (80:18:2 CHCl3:MeOH: conc. ammonium hydroxide (NH4OH)) in CHCl3) to give an off-white solid. The solid was triturated with diethyl ether (Et2O) and collected by vacuum filtration to yield 1-(3-{[4-amino-2-(ethoxymethyl)-1H-imidazo[4,5-c]quinolin-1-yl]amino}propyl)-3-isopropylurea (0.603 g) as an off-white solid. mp 174–177° C.; 1H NMR (300 MHz, DMSO-d6) δ 8.45 (d, J=8.1 Hz, 1H), 7.58 (d, J=8.2 Hz, 1H), 7.46–7.41 (m, 1H), 7.26–7.22 (m, 1H), 6.96 (t, J=5.5 Hz, 1H), 6.60 (s, 2H), 5.72 (t, J=5.5 Hz, 1H), 5.59 (d, J=7.7 Hz, 1H), 4.75 (s, 2H), 3.70–3.58 (m, 3H), 3.19–3.08 (m, 4H), 1.72–1.63 (m, 2H), 1.17 (t, J=7.0 Hz, 3H), 0.99 (d, J=6.5 Hz, 6H); 13C NMR (75 MHz, DMSO-d6) δ 157.8, 152.3, 149.5, 145.3, 132.4, 127.4, 126.1, 124.2, 121.2, 114.7, 65.9, 63.1, 50.2, 41.2, 37.4, 28.9, 23.6, 15.4; MS (APCI) m/z 400 (M+H)+; Anal. Calcd for C20H29N7O2: C, 60.13; H, 7.32; N, 24.54; Found: C, 59.94; H, 7.58; N, 24.45.
