Discovery and Optimization of Dihydroquinolin-2(1H)-ones as Novel Highly Selective and Orally Bioavailable Phosphodiesterase 5 Inhibitors for the Treatment of Pulmonary Arterial Hypertension

Phosphodiesterase 5 (PDE5) is a cGMP-specific hydrolytic enzyme and widely distributed in versatile tissues. PDE5 has been identified as a valid therapeutic target for treating erectile dysfunction and pulmonary arterial hypertension (PAH). Herein, a hit-to-lead structural optimizations were performed on the PDE1 inhibitor