Modular Access to Complex Prodiginines: Total Synthesis of (+)-Roseophilin via its 2-Azafulvene Prototropisomer

Ansa-bridged, prodiginines are bioactive pigments produced by bacteria. Certain of these structures are reported to be antagonists of protein protein interactions involved in apoptosis. We describe a new entry to alkaloids of this type, demonstrated with a concise asymmetric synthesis of (+)-roseophilin (3). Our route constructs the pyrrolophane motif via phosphoryl transfer-terminated macroaldolization and passes through a previously unexplored prototropic form of the natural product.