Synthesis of the Tetracyclic Core of the Daphlongeranines.

The first synthesis of the tetracyclic core of the daphlongeranine natural product family is reported. Containing a tricyclic core unique to this subfamily of the Daphniphyllum alkaloids and featuring two quaternary carbons, this 11-step synthetic route featured the application of a three-step spirocyclization strategy and development of a new intramolecular Pd-catalyzed cyclization reaction. Additionally, the route included the application of an XAT-initiated Giese addition and demonstration of an enantioselective synthesis of the bicyclic core.