Organobismuth Compounds as Aryl Radical Precursors via Light-Driven Single-Electron Transfer

Area of Science:

• Organic Chemistry
• Photochemistry
• Radical Chemistry

Background:

• Aryl radicals are crucial intermediates in organic synthesis.
• Existing methods for aryl radical generation often have limitations.
• Triarylbismuth reagents offer potential for novel radical generation pathways.

Purpose of the Study:

• To develop a novel light-driven method for aryl radical generation.
• To explore the mechanism of aryl radical formation from organobismuth compounds.
• To demonstrate the utility of this method in various arylation reactions.

Main Methods:

• Photochemical activation of triarylbismuth(III) and (V) reagents.
• Generation of an organobismuth(IV) intermediate.
• Ligand-assisted mesolytic cleavage for radical formation.
• Radical trapping and radical clock experiments for mechanistic studies.
• Computational studies to support the proposed mechanism.

Main Results:

• Successful generation of aryl radicals from triarylbismuth reagents using light.
• Proposed mechanism involving ligand-assisted mesolytic cleavage of a Bi(IV) intermediate.
• Demonstrated compatibility with diverse bimolecular radical arylations.
• Experimental evidence (trapping, clock) supporting aryl radical intermediacy.
• Computational validation of Bi(IV)-aryl mesolysis.

Conclusions:

• A novel and efficient light-driven method for aryl radical generation from organobismuth compounds has been established.
• The mechanism proceeds via a proposed organobismuth(IV) intermediate undergoing mesolytic cleavage.
• This methodology broadens the scope of radical arylation reactions, offering a versatile synthetic tool.