Intermolecular C-C/C-N σ-bond metathesis enabled by visible light.

Area of Science:

• Organic Chemistry
• Photochemistry
• Catalysis

Background:

• Transition-metal catalysis is established for π-bond metathesis but struggles with challenging σ-bond activation due to high bond energies.
• Activating C-C and C-N σ-bonds for metathesis reactions remains a significant hurdle in synthetic chemistry.

Purpose of the Study:

• To introduce a novel photo-induced strategy for C-C and C-N σ-bond metathesis.
• To achieve cross-coupling of tertiary amines with α-diketones without transition metals or photosensitizers.

Main Methods:

• Development of a transition-metal-free, photo-induced reaction protocol.
• Utilizing controlled experiments, intermediate trapping, and Density Functional Theory (DFT) calculations to elucidate the reaction mechanism.

Main Results:

• Successful cross-coupling of tertiary amines and α-diketones via C-C and C-N single bond cleavage and recombination.
• Formation of aryl alkyl ketones and aromatic amides in good to high yields.
• Demonstrated excellent functional group compatibility under metal- and photosensitizer-free conditions.

Conclusions:

• The study presents a groundbreaking, metal-free photo-induced method for σ-bond metathesis.
• The findings offer a new pathway for synthesizing valuable organic compounds, overcoming limitations of traditional catalytic methods.
• Detailed mechanistic studies provide a fundamental understanding of this novel transformation.