Nitrogen-Centered Organic Persistent Radicals Catalyze Redox-Neutral C─C Bond Forming Reactions.

Area of Science:

• Organic Chemistry
• Catalysis
• Radical Reactions

Background:

• Single electron transfer (SET) is crucial for radical transformations.
• Existing methods often rely on transition metals, photoredox catalysts, or mechanoredox mediators.
• Organic super electron donors and nitroxides face self-inhibition issues in these reactions.

Purpose of the Study:

• To introduce Kuhn-verdazyls as effective ground-state redox organocatalysts.
• To demonstrate their utility in SET-initiated radical transformations.
• To showcase their advantages over existing catalytic systems.

Main Methods:

• Utilizing Kuhn-verdazyls as redox organocatalysts.
• Investigating single electron shuttling capabilities.
• Applying catalysts to C-C bond-forming reactions like C-H arylation and trifluoromethylation.

Main Results:

• Kuhn-verdazyls function as tunable, ground-state redox organocatalysts.
• They effectively mediate SET radical transformations without light or external stimuli.
• Redox-neutral C-C bond formation was achieved, including C-H arylation and trifluoromethylation.
• These radicals avoid the self-inhibition issues seen with other organic catalysts.

Conclusions:

• Kuhn-verdazyls represent a novel class of organocatalysts for SET radical chemistry.
• They offer a metal-free, stimulus-free alternative for important C-C bond-forming reactions.
• Their unique properties overcome limitations of existing organic electron donors and nitroxides.