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. 4-[(6,7-Dimethoxy-4-quinolyl)oxy]aniline (50 mg) was dissolved in toluene (5 ml) and ethanol (1 ml), and a solution of 2,3-dimethyl-1-benzenecarbonyl isothiocyanate in ethanol (1 ml) was 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 (81 mg, yield 98%).
