Some syntheses via benzyne intermediates

This is attributed to protonolysis of the arylcopper intermediate. Protonolysis can become the dominant reaction under conditions where protonation is favorable. Most of these reactions are carried out under heterogeneous conditions but homogeneous conditions can be obtained with certain soluble copper(I) salt, particularly copper(I) trifluoromethanesulfonate.  

Perhaps the most important preparative use of aryl free radicals is in the synthesis of biaryls. If an aryl free radical is generated in the presence of a second aromatic compound, substitution leading to the biaryl is observed. Yields in this 

SECTION 8.3. FREE-RADICAL AND ELECTRON-TRANSFER PROCESS 

Ruchardt and B. Freudenberg, Tetrahedron Lett., 3623 (1964) C. Ruchardt and E. Merz, Tetrahedron Lett., 2431 (1964). 

Recent mechanistic investigations have defined a group of nucleophilic aromatic substitutions which proceed by a pathway described as SrnI. The key is an electron transfer from the nucleophile to an aryl halide. The process is a chain 

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