Highly enantioselective [4 + 2] annulations catalyzed by amino acid-based phosphines: Synthesis of functionalized cyclohexenes and 3-spirocyclohexene-2-oxindoles

The 3,3'-pyrrolidinyl-spirooxindole unit is a privileged heterocyclic motif that forms the core of a large family of alkaloid natural products with strong bioactivity profiles and interesting structural properties. Significant recent advances in the synthesis of this fused heterocyclic system have led to intense interest in the development of related compounds as potential medicinal agents or biological probes.