Palladium-Catalyzed Diastereo- and Enantioselective [3 + 2] Cycloaddition of Vinylcyclopropanes with Azadienes: Efficient Access to Chiral Spirocycles.

Benzofuran-derived azadienes (BDAs) have been widely used as four-atom synthons in transition-metal-mediated cycloaddition reactions, while the exploitation of their reactivity as a two-atom unit to construct spirocycles is still underdeveloped. Herein, we reported the first palladium(0)-catalyzed diastereo- and enantioselective [3 + 2] annulation of vinylcyclopropanes (VCPs) and BDAs. This transformation is featured with a broad substrate scope (31 examples), allowing for facile access to a variety of enantioenriched spirocycles bearing a quaternary stereogenic center in good yields with excellent regio-, diastereo-, and enantioselectivities (up to 93% yield, >20:1 dr, and mostly >99% ee) under mild reaction conditions. Moreover, the spirocyclic products could be efficiently converted to structurally complex tricyclo[8.3.0.0]-azatridecane and tricyclo[7.3.0.0]-azadodecane skeletons.