Toluene (20 ml) and thionyl chloride (1 ml) were added to commercially available 2,3-dimethylbenzoic acid (80 mg), and the mixture was heated at 100° C. for one hr. The solvent was removed by distillation, and 2,3-dimethyl-1-benzenecarbonyl isothiocyanate was prepared using the resultant 2,3-dimethyl-1-benzenecarbonyl chloride as a starting compound according to the description of the literature. 2,3-Dimethyl-1-benzenecarbonyl isothiocyanate was dissolved in ethanol (1 ml) to prepare a solution. 3-Chloro-4-[(6,7-dimethoxy-4-quinolyl)oxy]aniline (50 mg), toluene (5 ml), and ethanol (1 ml) were added to the solution, and the mixture was stirred at room temperature for 2 hr. The reaction solution was concentrated, and the residue was purified by chromatography on silica gel using chloroform/acetone for development to give the title compound (76 mg, yield 96%).
