A mixture of tert-butyl {[6-hydroxy-2-isobutyl-4-(4-methylphenyl)quinolin-3-yl]methyl}carbamate (1.5 g, 3.5 mmol), methyl bromoacetate (0.92 g, 6.0 mmol), potassium carbonate (0.55 g, 4.0 mmol) and N,N-dimethylformamide (5 ml) was stirred at room temperature for 4 hrs. Water was added to the reaction mixture and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, and dried over anhydrous magnesium sulfate. The residue was purified by silica gel column chromatography to give methyl {[3-{[(tert-butoxycarbonyl)amino]methyl}-2-isobutyl-4-(4-methylphenyl)quinolin-6-yl]oxy}acetate (1.9 g, yield 94%) as pale-yellow crystals.
