A solution of 7-benzyloxy-2-ethoxymethyl-N1-isopropyl-1H-imidazo[4,5-c]quinoline-1,4-diamine (1.67 g, 4.12 mmol) in 25 mL of toluene and 25 mL of methanol was treated with palladium on carbon (0.44 g, 0.42 mmol, 10% w/w). The mixture was shaken under an atmosphere of hydrogen (3.8×105 Pa). After 16 h, the reaction was filtered through a pad of CELITE filter agent and rinsed with solvent until the filtrate ran clear. The filtrate was concentrated under reduced pressure to provide a white solid. Purification by chromatography (SiO2, 3:1 CHCl3:(80:18:2 CHCl3:MeOH:NH4OH) gradient to 1:1) gave 0.50 g of 4-amino-2-ethoxymethyl-1-isopropylamino-1H-imidazo[4,5-c]quinolin-7-ol as a white solid. MS (APCI) m/z 316 (M+H)+.
