Total synthesis of (±)-communesin F

Total synthesis of the complex polycyclic indole alkaloid (+/-)-communesin F has been accomplished in 23 reaction steps in about 3% overall yield. The key steps relied on a highly efficient methodology for assembling the pentacyclic substructure 2 with the C7 quaternary carbon, the stereoselective preparation of the second C8 quaternary carbon by a two-step one-pot O-allylation and consecutive 3,3-rearrangement (2 to 3), and the stereoselective acid-catalyzed cyclization of 4 to form the azepine ring (5). These highly stereoselective reactions guaranteed the stereochemical results, allowing the construction of the C, E, F, and G ring systems.