Construction of spiro-oxaquinolizidinone framework of Upenamide via organoiron complexes

An organoiron approach toward the synthesis of an elaborated tricyclic spiro-oxaquinolizidinone ring has been accomplished. The key intermediate was efficiently prepared through a nitrile addition to the appropriately functionalized cyclohexadienylium–Fe(CO)3 perchlorate salt to install the requisite quaternary center in the spiro-oxaquinolizidinone ring.