Nickel-Catalyzed Radical-Radical Cross-Coupling Reactions

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Nickel-catalyzed radical cross-coupling has become a powerful tool for forming C-C and C-heteroatom bonds.
• It utilizes open-shell intermediates under mild reaction conditions.

Purpose of the Study:

• To review recent advancements in nickel-catalyzed radical cross-coupling.
• To emphasize dual radical sorting as a unifying mechanistic framework.

Main Methods:

• Focus on nickel catalysts for selective differentiation and cross-coupling of multiple radical species.
• Exploration of inner-sphere organonickel pathways and outer-sphere processes, including bimolecular homolytic substitution (S_H2).
• Highlighting triple radical sorting for multicomponent alkene difunctionalization.

Main Results:

• Demonstration of nickel catalysts enabling selective coupling across C(sp²)-C(sp³), C(sp³)-C(sp³), and C(sp³)-heteroatom bonds.
• Successful application of dual radical sorting across various bond-forming reactions.
• Emergence of triple radical sorting for complex difunctionalization reactions.

Conclusions:

• Nickel-catalyzed radical cross-coupling, unified by dual radical sorting, provides a versatile platform for diverse bond formations.
• Future directions include addressing challenges in asymmetric radical sorting and selective primary-primary radical coupling.