DMF (150 mL), pyridine (10 mL), and 1,1′-carbonyldiimidazole (16.7 g, 103 mmol) were added to tert-butyl 3-{[(3-amino-2-chloroquinolin-4-yl)amino]methyl}benzylcarbamate (17.03 g, 41.24 mmol), and the reaction was heated at 80° C. overnight and allowed to cool. The volatiles were removed under reduced pressure. The residue was mixed with ethyl acetate, collected by filtration, and dried under vacuum for two hours to provide 12.06 g of tert-butyl 3-[(4-chloro-2-hydroxy-1H-imidazo[4,5-c]quinolin-1-yl)methyl]benzylcarbamate as a white solid.
