Synthesis of the Tetracyclic Core of the Daphlongeranines.

Shennan BDA, Smith PW, Ogura Y, Källström EA, Moustakim M, Balan T, Dixon DJ

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.