Enantiocontrolled Total Synthesis of (-)-Retigeranic Acid A.

The asymmetric total synthesis of (-)-retigeranic acid A has been realized. The key features of the current synthesis include (1) a Pt-catalyzed Conia-ene 5-exo-dig cyclization of enolyne to establish the key quaternary stereochemical center of C-10 (D/E ring), (2) an intramolecular diastereoselective Prins cyclization to construct the trans-hydrindane backbone (A/B ring), and (3) a late-stage intramolecular Fe-mediated hydrogen atom transfer (HAT) Baldwin-disfavored 5-endo-trig radical cyclization to rapidly assemble vicinal quaternary centers and the core structure of (-)-retigeranic acid A (C ring).