Reaction Steps
A solution of N1-(3-aminopropyl)-2-ethoxymethyl-1H-imidazo[4,5-c]quinoline-1,4-diamine (1.42 g, 4.52 mmol) in 25 mL of CH2Cl2 was placed under an atmosphere of nitrogen and chilled in an ice water bath. The solution was slowly treated with ethyl isocyanate (0.375 mL, 4.74 mmol). Upon addition the reaction mixture became thick and additional CH2Cl2 had to be added to keep the mixture stirring. The reaction was allowed to slowly warm to ambient temperature. After 17 h, the reaction was concentrated under reduced pressure to yield an off-white solid. The solid was purified by chromatography (SiO2, 15–50% (80:18:2 CHCl3:MeOH:NH4OH) in CHCl3) to yield an off-white solid. The solid was recrystallized from MeCN to give 1-(3-{[4-amino-2-(ethoxymethyl)-1H-imidazo[4,5-c]quinolin-1-yl]amino}propyl)-3-ethylurea (1.16 g) as a white solid. mp 138–141° C.; 1H NMR (300 MHz, DMSO-d6) δ 8.45 (dd, J=8.1, 1.0 Hz, 1H), 7.58 (dd, J=8.3, 0.9 Hz, 1H), 7.46–7.41 (m, 1H), 7.27–7.21 (m, 1H), 6.96 (t, J=5.6 Hz, 1H), 6.60 (s, 2H), 5.83 (t, J=5.7 Hz, 1H), 5.73 (t, J=5.5 Hz, 1H), 4.75 (s, 2H), 3.61 (q, J=7.0 Hz, 2H), 3.20–3.08 (m, 4H), 3.03–2.94 (m, 2H), 1.68 (p, J=6.9 Hz, 2H), 1.17 (t, J=7.0 Hz, 3H), 0.96 (t, J=7.1 Hz, 3H); 13C NMR (125 MHz, DMSO-d6) δ 158.4, 152.3, 149.5, 145.3, 132.4, 127.4, 126.1, 124.2, 121.3, 121.2, 114.8, 65.9, 63.1, 50.2, 37.6, 34.4, 28.9, 16.0, 15.4; MS (ESI) m/z 386 (M+H)+; Anal. Calcd for C19H27N7O2•0.5H2O: C, 57.85; H, 7.15; N, 24.85; Found: C, 57.84; H, 7.31; N, 25.04.
