The condensation of 4-chloro-3-nitroquinoline (I) with isobutylamine in refluxing THF gives 4-(isobutylamino)-3-nitroquinoline (II), which by reduction with H2 over Pt/C in ethanol is converted to 3-amino-4-(isobutylamino)quinoline (III). The cyclization of (III) with triethyl orthoformate in refluxing formic acid affords 1-isobutyl-1H-imidazo[4,5-c]quinoline (IV), which is oxidized with 30% H2O2 in hot acetic acid yielding 1-isobutyl-1H-imidazo[4,5-c]quinolin-5-oxide (V). The reaction of (V) with refluxing POCl3 affords 4-chloro-1-isobutyl-1H-imidazo[4,5-c]quinoline (VI), which is finally treated with concentrated aqueous NH4OH at 150 C in a pressure vessel.

The condensation of 4-chloro-3-nitroquinoline (I) with isobutylamine in refluxing THF gives 4-(isobutylamino)-3-nitroquinoline (II), which by reduction with H2 over Pt/C in ethanol is converted to 3-amino-4-(isobutylamino)quinoline (III). The cyclization of (III) with triethyl orthoformate in refluxing formic acid affords 1-isobutyl-1H-imidazo[4,5-c]quinoline (IV), which is oxidized with 30% H2O2 in hot acetic acid yielding 1-isobutyl-1H-imidazo[4,5-c]quinolin-5-oxide (V). The reaction of (V) with refluxing POCl3 affords 4-chloro-1-isobutyl-1H-imidazo[4,5-c]quinoline (VI), which is finally treated with concentrated aqueous NH4OH at 150 C in a pressure vessel.