Abstract

The arylation of unsaturated compounds by diazonium salts with copper salt catalysis was first disclosed by Meerwein. Meerwein arylation proceeds best when the double bond is activated by an electron attracting groups such as carbonyl, cyano, aryl, vinyl, ethynyl or chloro. The net result is the union of the aryl group with the carbon atom beta to the activating group, either by substitution of a beta-hydrogen atom of by addition of Ar and Cl to the double bond. The generally accepted mechanism of the reaction involves the aryl radical from the diazonium salt, though the manner of its formation and subsequent reaction is still controversial