Polyether Natural Product Inspired Cascade Cyclizations: Autocatalysis on π-Acidic Aromatic Surfaces

Area of Science:

• Catalysis
• Organic Chemistry
• Supramolecular Chemistry

Background:

• Anion-π catalysis stabilizes anionic transition states on aromatic surfaces.
• This interaction is suitable for long-distance charge displacements.
• Aromatic surfaces with positive quadrupole moments are key for anion-π interactions.

Purpose of the Study:

• To develop an anionic cascade reaction analogous to cation-π biocatalysis.
• To investigate anion-π-catalyzed epoxide-opening ether cyclizations.
• To explore autocatalysis in these reactions.

Main Methods:

• Utilizing π-acidic aromatic surfaces (e.g., hexafluorobenzene, naphthalenediimides).
• Investigating the cyclization of polyether oligomers.
• Analyzing reaction kinetics and substrate concentration dependence.

Main Results:

• Anion-π catalysis achieved exceptionally high autocatalysis (k_auto /k_cat >10⁴ m^-1) for epoxide-opening ether cyclizations.
• Reactions proceeded effectively on specific π-acidic aromatic surfaces.
• Observed complex reaction mechanisms including Goldilocks-type substrate concentration dependence.

Conclusions:

• Anion-π catalysis provides a powerful new method for molecular transformations, particularly cascade reactions.
• The high autocatalysis observed opens new avenues for catalyst and reaction design.
• Further research into the unique mechanistic features can lead to novel synthetic strategies.