Eosin Y Promoted C–H Arylation of Heteroarenes with Aryl Diazonium Salts

Key words

visible light - C–H arylation - heteroarenes - aryl diazonium salts

Significance

König and co-workers have developed a metal-free, direct intermolecular C–H arylation of heteroarenes with aryl diazonium salts by photoredox catalysis with green light. The reaction proceeds smoothly at room temperature, does not require transition-metal catalysts or bases, and displays a broad scope toward diazonium salts and heterocycles with a wide range of functional group tolerance. A suggested radical mechanism has been proposed based on experimental observations and literature data.

Comment

Arylated heteroarenes are widely used in materials science because of their interesting optical and electronic properties, but also in biomedical applications as peptide mimetics or drugs. Herein, the authors report a metal-free, direct intermolecular C–H arylation of heteroarenes with aryl diazonium salts by photoredox catalysis with green light. This single-electron transfer cross-coupling represents an efficient alternative to known transition-metal-catalyzed methods and may find applications beyond synthesis, such as in the chemical patterning of surfaces.