Asymmetric Dieckmann Condensation towards Spirocyclic Oxindoles Catalyzed by Amino Acid-derived Phosphonium Salts

An asymmetric Dieckmann condensation towards spirocyclic oxindoles and aza-oxindoles catalyzed by amino acid-derived phosphonium salt has been developed, which expanded the applicability of asymmetric phosphonium salt catalysis in the production of 1,3-dicarbonyl compounds. This reaction is distinguished by its mild conditions (-20 degrees C), low catalyst loading (3-5 mol%), and broad substrate scope (25 examples). Control experiments revealed that both the catalyst's phosphonium skeleton and H-bonding site were required. Product transformations and a gram scale experiment were also carried out.

Automated summary

An asymmetric Dieckmann condensation towards spirocyclic oxindoles and aza-oxindoles catalyzed by amino acid-derived phosphonium salt has been developed, which expands the applicability of asymmetric phosphonium salt catalysis in the production of 1,3-dicarbonyl compounds. The reaction features mild conditions, low catalyst loading, and a broad substrate scope. Control experiments confirmed the necessity of the catalyst's phosphonium skeleton and H-bonding site.