Synthesis of Spiro-isoindolinone Indenones via Double Nucleophilic Substitution: Application to the Total Synthesis of Impatien A

An efficient synthetic approach to spiro-isoindolinone-indenone scaffolds via a base-promoted double nucleophilic substitution reaction was developed. Two-step and one-pot protocols were established, delivering high yields and a broad substrate scope with excellent functional group tolerance. The synthetic utility of the spirocyclic ketone was demonstrated by performing various transformations, such as Wittig olefination, reduction, and Grignard addition. Furthermore, this methodology was successfully applied to the total synthesis of Impatien A in a five-step sequence involving benzylation, spirocyclization, and olefination.