Strategies for Enantioselective, Cascade, Valorizing, and Expanded Heterocyclic Piancatelli Rearrangements

Area of Science:

• Organic Chemistry
• Asymmetric Catalysis
• Sustainable Chemistry

Background:

• The Piancatelli rearrangement is a key method for synthesizing cyclopentenones from furan derivatives.
• Advances are needed to expand its scope and efficiency for complex molecule synthesis.

Purpose of the Study:

• To highlight recent advancements in the Piancatelli rearrangement.
• To showcase its application in enantioselective catalysis, cascade reactions, biomass valorization, and heterocyclic chemistry.

Main Methods:

• Utilizing chiral Brønsted acid catalysis, often with photoredox or transition-metal cocatalysis.
• Employing cascade reactions merging the rearrangement with Diels-Alder, hydroamination, or Friedel-Crafts reactions.
• Applying the rearrangement to biomass-derived furans like 5-hydroxymethylfurfural (HMF) and 5-azidomethylfurfural (AMF).

Main Results:

• Achieved highly enantio- and diastereoselective aza- and oxa-Piancatelli rearrangements.
• Developed three-component radical-mediated couplings for single-step functionalization.
• Enabled efficient synthesis of complex polycyclic frameworks with multiple stereocenters.
• Transformed HMF and AMF into bioactive cyclopentenones under sustainable conditions.
• Extended the rearrangement to pyrrole substrates for new photoswitches.

Conclusions:

• The Piancatelli rearrangement is a powerful and versatile tool for organic synthesis.
• Recent developments offer exciting opportunities in asymmetric synthesis, materials science, and heterocyclic chemistry.
• The reaction's adaptability from renewable feedstocks highlights its potential in sustainable chemistry.