2,2-Bifunctionalization of Norbornene in Palladium-Catalyzed Domino Annulation.

A palladium-catalyzed three-component [2 + 3 + 1] domino annulation among 3-iodochromones, α-bromoacetophenones, and norbornene is presented, affording various chromone-containing polycyclic compounds bearing fused/spiro/bridged-ring systems. For the first time, the 2,2-bifunctionalization of norbornene was realized in palladium-catalyzed domino reaction. This cyclization characterizes three new bonds (two C-C and one C-O) in a single operation and produces nontrivial spiro-norbornane fragments in comparison with a traditional palladium-catalyzed process involving norbornene.