Electrochemical Formation of Cinnamaldehyde by the Electrolyte System N,N-Diisopropylethylamine and 1,1,1,3,3,3-Hexafluoropropan-2-ol

The use of a supporting electrolyte has been a significant issue in electro-organic chemistry because it can be wasteful and increase steps in terms of separation from target products. However, it is ideal for an electrolyte to play multiple roles in reactions, for example, as a feedstock or catalyst. We have discovered that the combination of N,N-diisopropylethylamine (DIPEA) and 1,1,1,3,3-hexafluoropropan-2-ol (HFIP) not only works as an electrolyte but also facilitates the electrochemical formation of cinnamaldehyde from benzaldehydes. We demonstrate that the synthesis of 20 cinnamaldehyde derivatives can be achieved by using this reaction. Isotope-labeling experiments and C-13 NMR investigations revealed the mechanistic aspects of this process, and confirmed that DIPEA is the C2 synthon of acetaldehyde and HFIP could also function as a Bronsted acid.