6,8-Difluoro-2-[3-fluoro-4-[(3-phthalimidopropyl)amino]phenyl]-5-hexylamino-4H-1-benzopyran-4-one → 2-[4-(3-Aminopropylamino)-3-fluorophenyl]-6,8-difluoro-5-hexylamino-4H-1-benzopyran-4-one

60 mg of Compound 32 was dissolved in 30 ml of a mixed solvent of dimethylformamide and methanol, 0.050 ml of hydrazine monohydrate was added and the mixture was stirred at 60° to 70° C. for 4.3 hours. The reaction solution was concentrated under reduced pressure, and the residue was subjected to preparative thin layer chromatography (chloroform:methanol:aqueous ammonia=9:1:1) to give Compound 33 which was dissolved in chloroform. A 5.5N hydrochloric acid-isopropylalcohol solution was added, the solvent was distilled off under reduced pressure and the residue was treated with isopropyl ether to form the slurry from which 33.6 mg (67%) of hydrochloride of Compound 33 was obtained.