Nickel-Catalyzed Cycloaddition of α,β,γ,δ-Unsaturated Ketones with Alkynes

As easy as α, β, γ, δ: The title reaction unexpectedly resulted in the stereoselective synthesis of bicyclo[3.1.0]hexenes (see scheme). The high level of stereoselection is attributed to a mechanistic pathway involving the oxidative cyclization of nickel(0) with α,β,γ,δ‐unsaturated ketones and alkynes, and the subsequent intramolecular carbonickelation.