Synthesis and SAR of tetracyclic pyrroloquinolones as phosphodiesterase 5 inhibitors Original Research Article

The synthesis of the fused tetracyclic pyrroloquinolones 9a–i in four steps is described. The PDE5 inhibitory activities of these compounds, their selectivities against PDE1, PDE2, PDE3, PDE4 and PDE6, the preclinical pharmacokinetic assessments and the in vivo efficacy in increasing intracavernosal pressure are presented and discussed.