I-2-induced cascade cyclization and dearomatization of indoles for the highly efficient synthesis of iodinated and vinylic spiroindolenines

The spiroindolenine framework is a privileged heterocyclic motif and is widely present in numerous indole alkaloids. Herein, we develop a metal-free and environmentally friendly approach for the intramolecular cascade cyclization and dearomatization of indole derivatives to selectively afford iodinated and vinylic spiroindolenines by a substrate-controlled strategy. Simple operation, mild conditions, and high yield make this strategy a green and attractive pathway to construct functionalizable spiroindolenine scaffolds, which could be converted into diverse useful spiroindolenine derivatives.