4-Chloro-1-(2-methylpropyl)-1H-imidazo[4,5-c]quinoline is prepared by the reaction of 2-chloro-N
4-(2-methylpropyl)quinoline-3,4-diamine and orthoformic acid triethyl ester. The specific synthesis steps are as follows:
A suspension of 2-chloro-N4 -(2-methylpropyl)-3,4-quinolinediamine (35 g) and triethylorthoformate (52.3 g, 2.5 eq) was heated at 145° C. for 10 h, during which time ethanol was removed by distillation. The resulting mixture was cooled to room temperature and the solid was removed by filtration. The solid was dissolved in hydrochloric acid (100 mL, 4N). The resulting solution was added to a solution of sodium hydroxide. The precipitate was filtered and washed with water to afford the product 4-chloro-1-(2-methylpropyl)-1H-imidazo[4,5-c]quinoline in 92% yield.