A reactor was charged with 2 mmol of tert-butyl 2-oxo-3,4-dihydroquinoline-1(2H)-carboxylate (ai1) obtained in Synthesis Example 1 and 6.9 mL of tetrahydrofuran as a solvent to prepare a solution. After cooling the solution to −78° C. using dry ice, 2.0 mL (1.1 M, 2.2 mmol) of phenyllithium (PhLi) was slowly added dropwise to the solution. The mixture was reacted at −78° C. for 7 hours with stirring. The mixture including the reaction product was added to an ammonium chloride aqueous solution (5 mL), and the mixture was stirred. The mixture was extracted twice with ethyl acetate, and the reaction product was washed with a sodium chloride solution. After the addition of excess anhydrous magnesium sulfate to the collected organic layer, the solvent was evaporated under reduced pressure to obtain a concentrate including a crude product. The concentrate was subjected to silica gel flash column chromatography (eluant: hexane/ethyl acetate=6/1) to obtain tert-butyl 2-(3-oxo-3-phenylpropyl)phenylcarbamate (white solid) represented by the following formula (an1) (yield: 78%). The analysis data for the resulting aniline derivative (an1) is shown below.
