Synthesis of the tetracyclic ABCD ring systems of madangamines D-F.

Synthesis of the tetracyclic cores of madangamines D-F was achieved, featuring a reductive radical process from an ethoxycarbonyldichloroacetamide to build the morphan nucleus, a Mitsunobu-type aminocyclization toward the common diazatricyclic intermediate, and ring-closing metathesis reactions for the macrocyclization step leading to the 13- to 15-membered rings.