Photoinduced Halogen Bond Assisted Biaryl Synthesis via 1,4-Aryl Migration

Area of Science:

• Organic Chemistry
• Synthetic Methodology
• Photochemistry

Background:

• Biaryl compounds are crucial structural motifs in pharmaceuticals and materials.
• Existing synthetic methods often require expensive catalysts or harsh conditions.
• Developing efficient and versatile biaryl synthesis strategies remains a key challenge.

Purpose of the Study:

• To develop a novel photoinduced, catalyst-free strategy for biaryl synthesis.
• To utilize halogen bonding to facilitate radical generation and subsequent rearrangement.
• To synthesize a broad range of structurally diverse and functionalized biaryl compounds.

Main Methods:

• Photoirradiation of N-aryl-2-iodobenzamides and N-sulfonyl-2-iodobenzamides.
• Employing halogen bonding to assist aryl radical generation.
• Investigating reaction mechanisms using TEMPO trapping, EPR, UV-vis, and NMR spectroscopy.
• Utilizing Density Functional Theory (DFT) calculations.

Main Results:

• A successful catalyst-free, photoinduced synthesis of biaryl compounds was achieved.
• Halogen bonding was confirmed to facilitate aryl radical formation.
• A Truce-Smiles-type rearrangement was identified as the key step.
• Mechanistic studies supported the involvement of radical intermediates and halogen bonding.
• DFT calculations provided insights into reaction selectivity and pathway.

Conclusions:

• The reported strategy offers an efficient and versatile route to diverse functionalized biaryls.
• The method avoids the need for metal catalysts, simplifying the process.
• This work expands the toolkit for constructing complex biaryl structures.