Tunable Palladium-Catalyzed [2π + 2σ] Cycloaddition/Alder-Ene Reactions of Vinylbicyclo[1.1.0]butanes with Cyclic N-Sulfonylimines.

A condition-controlled regiodivergent [2π + 2σ] cycloaddition/Alder-ene reaction of vinylbicyclo[1.1.0]butanes with cyclic N-sulfonylimines enabled by palladium catalysis is described. This protocol provides a wide range of azabicyclo[2.1.1]hexanes (aza-BCHs) in 30-71% yields with good to excellent selectivities. Additionally, cyclobutenes bearing two quaternary stereocenters are conveniently generated in good yields with excellent selectivities via a palladium-catalyzed Alder-ene reaction. This strategy features mild reaction conditions, a broad substrate scope, and excellent selectivities. Furthermore, scale-up reaction and derivatizations of the resulting aza-BCHs further demonstrate the practical utility of this protocol.