A solution of 6-hydroxy-7-(morpholinomethyl)benzofuran-3(2H)-one (0.170 g, 0.684 mmol) obtained in Example A41, Step 1 in methanol (3 mL) was added with 7-aza-1H-indole-3-carboxaldehyde (0.100 g, 0.684 mmol) and piperidine (0.00582 g, 0.0684 mmol), and the mixture was stirred at 60° C. for 1 hour. The reaction mixture was cooled to room temperature, and then added with methanol (2 mL), and the precipitated solid was suspended in methanol and thereby washed. The solid was collected by filtration to obtain the objective (Z)-2-[(1H-pyrrolo[2,3-b]pyridin-3-yl)methylene]-6-hydroxy-7-(morpholinomethyl)benzofuran-3(2H)-one (0.135 g, 52%).
