Alkylation of 3-aminophenol (I) with 2-(chloromethyl)quinoline (A) in a mixture of DMSO and THF employing sodium hydride as the base affords the intermediate amine (II). This amine is reacted with trifluoromethanesulfonic anhydride in toluene employing potassium carbonate as a base to afford ritolukast.
The reaction of 2-(chloromethyl)quinoline (I) with 3-nitrophenol (II) by means of Cs2CO3 in refluxing acetone gives the 3-nitrophenyl ether (III), which is reduced with H2 over Raney-Ni in ethanol to afford the 3-aminophenyl ether (IV). Finally this compound is sulfonated with trifluoromethanesulfonic anhydride and Et3N in dichloromethane.