Intermediates for Families of Reactions

An attractive concept is to use the electrode reaction to produce a reactive intermediate that can be used for in-situ reactions with a variety of substrates, leading to a family of larger molecules. Nematollahi and coworkers [21-23] have described a number of syntheses where 

The kinetics of the Michael additions are also conveniently studied by cyclic voltammetry. Utley and colleagues [24,25] have described a family of reactions based on the cathodic reduction of a,a-dibromo-l,2-dialkylbenzenes to o-quinodimethanes and trapping of these metastable intermediates by dienophiles in a Diels-Alder reaction. Here, a typical example is  

The mechanism of these reactions is not straightforward, however, as the dienophile can act as a redox mediator in the reduction of the a,a-dibromo-l,2-dialkylbenzene to o-quinodimethane as well as tfapping the reactive intermediate [26]. 

Yoshida and coworkers [27-29] have shown that it is possible to substantially extend the approach of electrogenerating a metastable intermediate and trapping with a nucleophile or electrophile by employing low temperatures and flow technology combined with the use of non-nucleophilic solvents, and have illustrated the approach with a wealth of examples. 

The early reports showed that a number of cations, normally not stable, could be generated by 2e oxidation in methylene dichloride at 195 K in a flow cell and then reacted with a number of nucleophiles in a second reactor  

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