Nucleophilic reactions between organic carbocations and nucleophiles are key in organic syntheses. However, these reactions can be problematic because the nucleophiles are usually oxidized more quickly than the organic substrates. Mahito Atobe and colleagues at the Tokyo Institute of Technology, Japan, have developed a novel electrocatalytic system that overcomes this problem. Atobe describes the new approach in the short interview below.

1.  Please explain, for a non-specialist, the significance of your article. 
This article describes a new approach to the in situ trapping of electrooxidatively generated electrophiles by nucleophiles. Under normal conditions, such reactions are problematic because of dominant oxidation of the nucleophile. The work capitalises on our earlier observation that in emulsified solutions the droplets do not undergo electron-transfer reactions unless electrolyte is absorbed by the droplet. Hence, a nucleophile that is not soluble in the electrolytic solution will not be oxidized. It will, however, react with an electrophile in solution. The combination leads to a very novel approach to making carbon - carbon bonds.

2.  What has motivated you to conduct this work?
Recently we have demonstrated successfully that direct electropolymerization of water-insoluble monomers proceeded in aqueous electrolytes using acoustic emulsification. Ultrasonication of the water-insoluble monomer-aqueous electrolyte mixtures allowed the formation of very stable emulsions without added surfactants, and smooth electropolymerization in the emulsions took place via direct electron transfer between the electrode and the water-insoluble monomer droplets. In this kind of biphasic electron transfer system, the supporting electrolyte should be dissolved not only in the aqueous phase but also in the monomer droplets and should contribute to the formation of an electric bilayer inside the droplets. Hence, when the droplet did not contain any supporting electrolytes, direct electron transfer was suppressed. These findings gave us the incentive to develop a novel electrochemical system that would realize the anodic substitution reaction without affecting the oxidation of the nucleophile in a one-step electrochemical operation.

3.  Where do you see this work developing in the future?
The presence of several substrates in a single reactor often causes interference with a desired reaction. To avoid this drawback, chemo-selective reactions (which represent an elegant approach to discriminate between substrates, allowing reaction of one in preference to others) have been developed and they are extensively used as an important tool in organic synthesis, catalysis, biological chemistry, etc. Our methodology will also realize facile and novel chemo-selective oxidation or reduction of a substrate even in the presence of other chemicals whose oxidation or reduction potentials are lower than that of the substrate.

4.  Are there any particular challenges facing future research in this area?
In the future work, we aim to improve the efficiency of this method and expand the scope of the substrates and reaction patterns. In particular, we will apply this system to amino acid derivatives which are one of the key groups one might want to functionalize.