Silver-Catalyzed Carbon Dioxide Fixation on Alkynylindenes

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Polycyclic indene derivatives are important structural motifs in various chemical applications.
• Efficient synthetic routes for constructing complex indene frameworks are highly sought after.
• Carbon dioxide utilization in organic synthesis presents a sustainable approach.

Purpose of the Study:

• To develop a novel silver-catalyzed cascade reaction for synthesizing polycyclic indene derivatives.
• To achieve carbon dioxide fixation onto 2-alkynylindene derivatives.
• To control the stereoselectivity of the intramolecular cyclization step.

Main Methods:

• Employing a silver catalyst to activate the alkyne moiety in 2-alkynylindene derivatives.
• Utilizing the indenyl anion for nucleophilic addition to carbon dioxide, forming a new carbon-carbon bond.
• Inducing an intramolecular cyclization cascade to form the polycyclic indene core.

Main Results:

• Successful synthesis of polycyclic indene derivatives through a silver-catalyzed cascade process.
• High yields of the desired products were obtained across various substrates.
• Demonstrated control over endo/exo selectivity via substrate substituents, achieving 6-endo-selective cyclization to afford α-pyrone-fused indenes.

Conclusions:

• A novel and efficient cascade reaction for polycyclic indene synthesis via CO2 fixation has been established.
• The developed methodology offers broad substrate scope and high yields.
• Stereochemical outcomes can be tuned by modifying substrate substituents, enabling access to specific fused indene structures.