摘要：A novel series of pyrido[ 1,2-e]purin-4（3H）-one derivatives co.taining polar substituents on 5＇-position were designed and prepared as potential PDE5 inhibitors. This paper reports the synthetic routes, 1H-NMR data, and the PDE5 inhibitory activities of the target co.pounds. The polar piperazinyl group co.tained （on 5＇-position） co.pound, 3B2, showed the highest activity among the tested derivatives but less potency than sildenafil 1.