Hari DP, Schroll P, König B * Universität Regensburg, Germany
Metal-Free, Visible-Light-Mediated Direct C–H Arylation of Heteroarenes with Aryl
Diazonium Salts.
J. Am. Chem. Soc. 2012;
134: 2958-2961
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.
