Diazonium ions alkyl, nucleophilic substitution

Nucleophilic substitution reactions that occur imder conditions of amine diazotization often have significantly different stereochemisby, as compared with that in halide or sulfonate solvolysis. Diazotization generates an alkyl diazonium ion, which rapidly decomposes to a carbocation, molecular nitrogen, and water ... 

The reaction of a-ketodiazonium ions is of interest because there is considerable evidence that loss of nitrogen can occur by an 8 2 mechanism (p. 337-347). If this is generally true, the possibility arises of a comparison between the reactions of diazonium ions and those of alkyl halides and tosylates under conditions that do not lead to the formation of carbonium ion intermediates. In the discussion of the molecularity of the rate-determining step, the reaction of ketodiazonium ions was supposed to proceed with simple substitution by an external nucleophile. Product analyses, on the reactions of diazoketones with acids and the deamination of aminoketones, show, however, that extensive rearrangement and molecular fragmentation can occur in suitable alkyl structures. The simplest of these reactions have the following stoichiometric form (Baumgarten and Anderson, 1961) ... 

Kirmse et al. (1991) came more closely to a differentiation between classical and nonclassical carbocation intermediates in deamination by the photolytic formation and nucleophilic substitution of diazonium ions from the 4-toluenesulfonyl hydrazones of 6,6-dimethyl- and 5,5,6,6-tetraalkylnorbornan-2-one 7.117, 7.118 and 7.119 (Scheme 7-36). By running the reactions in D20/Na0D, the diazonium ions were labeled with deuterium in the 2-position. For all three reagents, the alkylated exo-norbornanols (from 7.117 7.120 and 7.121) showed a distribution of deuterium in positions 1 and 2 that was very close to 1 1 (49.5 50.5 to 47.6 52.4). If these deviations from an equal distribution were caused by two classical ion intermediates. 

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