N‐Heterocyclic Carbene Catalyzed Stetter–Aldol Domino Cyclization To Synthesize Tetrahydronaphthalene‐Fused Spirooxindoles

Abstract A formal [4+2] annulation reaction of phthalaldehydes and 3‐ylideneoxindoles through a tandem process of a Stetter–aldol reaction was accomplished by the application N‐heterocyclic carbenes as effective catalysts. Under mild conditions, this unprecedented cascade reaction readily occurs in good yield, enabling straightforward access to functionalized tetrahydronaphthalene‐fused spirooxindoles. For the first time, the feasibility of an asymmetric Stetter–aldol reaction has also been briefly explored by employing chiral organic bases to promote the asymmetric transformation.