Enantioselective total synthesis of pyrroloquinolone as a potent PDE5 inhibitor

A concise enantioselective strategy for the synthesis of key phosphodiesterase-5 inhibitor 2 was developed via routes that proceeded in four steps and 72% overall yield, and in three steps and 58% overall yield, respectively, from imine 6 using asymmetric hydrogenation and one-pot chiral auxiliary reduction approaches.