To a solution of the compound (0.15 g) obtained in Example 404, 3-diethylaminopropionic acid hydrochloride (0.078 mg), Et3N (0.150 ml) and HoBt.H2O (0.083 mg) in DMF (2 ml), WSC.HCl (0.138 mg) was added, and the reaction mixture was stirred at room temperature for 12 hours. The reaction mixture was concentrated under reduced pressure, and then the residue was dissolved in ethyl acetate. The organic layer was washed with an aqueous saturated sodium bicarbonate solution and brine, dried, and then the solvent was evaporated under reduced pressure. The obtained residue was purified by preparative thin layer chromatography to obtain the title compound as pale yellow oil (0.100 g, 51%).
