Consecutive Multiphoton-Mediated Defluorinative Amination of Fluoroarenes

Area of Science:

• Organic Chemistry
• Photocatalysis
• Synthetic Methodology

Background:

• Traditional nucleophilic aromatic substitution (S_NAr) reactions often require harsh conditions.
• Developing milder and more versatile methods for fluoroarene functionalization is crucial.

Purpose of the Study:

• To develop a robust and general method for aromatic defluorinative amination under mild conditions.
• To utilize a novel strongly oxidizing photocatalyst for S_NAr reactions.

Main Methods:

• Employing the photocatalyst HATCN (hexaazatriphenylene core) for visible-light-mediated reactions.
• Investigating the multi-redox states of HATCN and their role in catalysis.
• Conducting mechanistic studies, including intermediate isolation and photon intensity dependence.

Main Results:

• Achieved aromatic defluorinative amination of fluorobenzenes under mild conditions.
• Demonstrated the photocatalyst HATCN's ability to access multiple redox states (neutral, monoanionic, dianionic).
• Established a catalytic cycle involving three photon absorptions and the distinct roles of HATCN redox states (oxidant/reductant).

Conclusions:

• HATCN is an effective oxidizing photocatalyst for S_NAr reactions, offering broad substrate scope.
• The multi-photon catalytic process driven by HATCN's redox flexibility represents a novel mechanistic paradigm.
• This method overcomes limitations of traditional S_NAr, enabling access to previously challenging fluoroarene derivatives.