1,8-Naphthyridin-2(1H)-ones 1 are a group of compounds possessing antibacterial, 2 antiinflammatory, 3 antiallergic, or antisecretory activites. 4 Among them, 4-aryl-1,8-naphthyridin -2(1H)-ones have recently attracted considerable interests: we examined acyl-CoA: cholesterol acyltransferase (ACAT) inhibitory activity 5 and developed SL-7665; Yamanouch group developed YM-10335 possessing phosphodiesterase inhibitory activity 6., and (Fig. 1).