Selective Synthesis of Imidazo[4,5- <i>f</i> ]- and Imidazo[4,5- <i>h</i> ]quinoline <i>N</i> -Oxides via Base-Catalyzed Cyclization of <i>ortho</i> -Nitroalkylaminoquinolines

We report an efficient base-catalyzed cyclization of readily available <i>ortho</i>-nitroalkylaminoquinolines for the synthesis of a series of imidazo-[4,5-<i>f</i>]-quinoline and imidazo-[4,5-<i>h</i>]-quinoline <i>N</i>-oxides. Using alkali metal alkoxides in anhydrous alcohol, we achieved good to excellent yields (up to 92%) of various <i>N</i>-oxides, allowing the corresponding <i>N</i>-oxidation products to be obtained selectively. The method is suitable for a wide range of substituents (except tertiary amines). This protocol opens a direct route to new, previously inaccessible imidazo-[4,5]-quinoline <i>N</i>-oxide derivatives, opening the way for future pharmacological studies, given their purine-like structures and potential therapeutic applications.