To a solution of 5-{[6-(methoxymethyl)pyridin-3-yl]oxy}-7-(tetrahydro-2H-pyran-4-yloxy)-1H-indole-2-carboxamide (1.45 g) in tetrahydrofuran (20 mL) was added a Lawesson's reagent (1.6 g), and the mixture was stirred with heating under reflux for 1 hr. The reaction mixture was cooled, and concentrated under reduced pressure. The obtained crude product was subjected to silica gel column chromatography (ethyl acetate:hexane=0:100 to 100:0, volume ratio) to give the title compound (1.5 g, yield 99%) as a yellow amorphous solid.
