Benzyl Bromide → Tert-butyl 8-amino-1-benzyl-1,2,3,4-tetrahydro-2-oxoquinolin-3-ylcarbamate

tert-Butyl 8-amino-2-oxo-1,2,3,4-tetrahydroquinolin-3-ylcarbamate produced in Example 6 (10 g) was added to N,N-dimethylformamide (100 mL), and sodium hydride (1.65 g) was added thereto under cooling on ice. The mixture was stirred at room temperature for one hour. Subsequently, under cooling on ice, benzyl bromide (6.48 g) was added to the mixture, and stirring was performed at room temperature for one hour. The reaction mixture was filtered, and the filtrate was concentrated under reduced pressure, to thereby recover a residue. The residue was purified through silica gel column chromatography (ethyl acetate: n-hexane=1:2), whereby the title compound (10.8 g) was yielded.