Assembly of Spirooxindole Derivatives Containing Four Consecutive Stereocenters by Using Cascade Reactions Catalyzed by an N‐Heterocyclic Carbene

In-spiro-ational: Biologically important and synthetically challenging spirocyclopentaneoxindoles with four consecutive stereocenters, including one spiroquaternary stereocenter, have been constructed in good yields and diastereoselectivity by a cascade reaction catalyzed by an N-heterocyclic carbene (see scheme). This reaction also provides a new strategy to access highly unusual tricyclic oxindoles.