NaH (1.260 g) was added to a solution of 3-[4-(benzyloxy)phenyl]-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-one (5 g) and 1-iodopropane (3.07 mL) in DMF (50 mL) at room temperature. The mixture was stirred at room temperature under a dry atmosphere (CaCl2 tube) for 1 h. The reaction mixture was diluted with MeOH and concentrated in vacuo. The residue was purified by column chromatography (NH silica gel, eluted with 0%-50% EtOAc in hexane) to give 3-[4-(benzyloxy)phenyl]-1-propyl-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-one (1.5 g) as dark yellow oil.
