Construction of Cyclopentanes Consisting of Five Stereocenters via NHC-Catalyzed Cascade Reactions of Enals with Oxindole-Dienones

Despite
the widespread presence of the chiral cyclopentane motif,
the asymmetric synthesis of cyclopentanes containing five stereocenters
remains a formidable challenge. Here, we present an N-heterocyclic carbene (NHC)-catalyzed cascade reaction of enal and
oxindole-dienone, which allows access to spiroxindole cyclopentanes
featuring a complete set of chiral centers on the five-membered carbocycle.
This strategy, characterized by the formation of multiple bonds and
chiral centers, demonstrates a broad substrate scope, exclusive diastereoselectivity,
and up to 99:1 er.