The above-mentioned aziridine compound (342 mg) was dissolved in mixture of methanol (10 mL) and water (2 mL), and sodium azide (439 mg) and ammonium chloride (155 mg) were added to the solution. The mixture was stirred at 60° C. for 40 hours. After the reaction mixture was cooled by standing, the reaction mixture was diluted with ethyl acetate, and the dilution was washed with saturated sodium hydrogen carbonate aqueous solution, water and saturated sodium chloride aqueous solution in this order, dried over anhydrous sodium sulfate, and concentrated in vacuo. The obtained residue was purified by silica gel column chromatography (C-300; hexane: ethyl acetate=2:1→1:1) to give the desired compound, 1-azido-1,1-bis(4-fluorophenyl)-2-propaneamine (251 mg). The above-mentioned azide compound (8 mg) was reduced in the presence of 10% palladium carbon catalyst (5 mg) in methanol under 1 atm hydrogen at room temperature. The catalyst was removed by filtration, and then the filtrate was concentrated in vacuo to give the title compound (7 mg).
