Free-radical diazocoupling. A new general reaction of diazonium salts

We now describe new general synthesis of alkylaryldiazenes on the basis of the reactions of Scheme I: - + N=N+-Ar -> RN=N.+-Ar (1) =N.+-Ar + M"+ -> RN=NAr + M(n+1)+ (2) alkyl radicals to arenediazonium cations (eq 1) and reduction of the intermediate azo radical cation adducts by metal salts (M"+, eq 2). Several sources of alkyl radicals R. were found suitable for this reaction.