Copper‐Catalyzed Asymmetric [2 + 2 + 2] Cycloaddition of Diynes via Vinyl Cations

Catalytic asymmetric [2 + 2 + 2] cycloaddition of diynes represents an efficient and atom-economical strategy for the assembly of valuable chiral cyclic targets in a single step. However, this strategy traditionally relies on the cyclometallation process. Moreover, there are no versatile asymmetric [2 + 2 + 2] cycloaddition methods for diynes that are compatible with C─C double/triple bonds and C─X double bonds. Here, we disclose a copper-catalyzed asymmetric [2 + 2 + 2] cycloaddition of diynes via vinyl cations. This universal [2 + 2 + 2] cycloaddition is suitable for the asymmetric cycloaddition of diynes with various C─C double/triple bonds and C─X double bonds, leading to a range of valuable chiral hexahydropyrrolocarbazoles, tetrahydropyrrolocarbazoles, and tetrahydropyran[4,3-b]indoles in generally excellent yields with excellent diastereo- and enantioselectivities. Importantly, this protocol features the first asymmetric [2 + 2 + 2] cycloaddition via vinyl cations, and constitutes the first construction of carbon stereocenters in triyne cyclization.