4-(5,6-Dimethyl-[2,2′]bipyridin-3-yloxy)-6-methoxy-quinolin-7-ol (compound 338) (80 mg) was dissolved in tetrahydrofuran (2 ml) to prepare a solution. Triphenylphosphine (112 mg), (2,2-dimethyl-[1,3]dioxan-5-yl)-methanol (38 mg), and diethylazodicarboxylate (0.078 ml) were added to the solution, and the mixture was stirred at room temperature for 6 hr. Further, 1 N sulfuric acid (4 ml) was added thereto, the mixture was stirred at room temperature overnight, and the reaction solution was brought to 0° C. and was stirred. The reaction solution was made alkaline by the addition of a 10% aqueous sodium hydroxide solution. Water was added thereto, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was then washed with saturated brine and was dried over anhydrous sodium sulfate. The solvent was removed by distillation under the reduced pressure, and the residue was purified by thin layer chromatography using chloroform-methanol to give the title compound (50 mg, yield 52%).
