Diazonium salts reductive cleavage

The cation 18 did not show any DNA cleavage, due probably to its inherent stability (18 would be more stable than a benzyl cation [66], relatively stable ions that do not alkylate the heterocyclic bases in DNA). The 9-diazofluorene 19 would not undergo reduction like the corresponding diazonium salts (17) because of the presence of a negative charge on the fluorenyl carbon. 

Arylamines from triazenes. Arylamines can be protected as triazenes (formation by reaction of the diazonium salts with a secondary amine). Regeneration of ArNH2 is accomplished by reductive cleavage using Al-Ni alloy in a basic solution. 

Oxidative cleavage of 280 by copper(ll) acetate generates a peroxy radical, which oxidizes the substrate to form an alcohol function and an oxy radical. Further reaction with the substrate affords again the corresponding alcohol in addition to a carbon radical. Thus, two equivalents of alcohol and only one equivalent of the carbon radical are formed. Since the reaction products originate from the carbon radical (see Fig. 112), the maximum yield could be 33%. The combined yields of 274 on one hand and 275-279 on the other hand are actually higher, hence further reduction of the alcohol must have occurred. It is very iikely that the copper(l) ion, which behaves as a moderately strong reductant (99), converts the alcohol, at least partially, to the reactive carbon radical. This mechanism explains the catalytic activity of copper(ll) acetate and resembles the reaction of arene diazonium compounds with copper(l) salts (100). 

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