Kolbe Electrolysis as a Novel Way of Generating Non-Proteinogenic Amino Acids

By using Kolbe electrolysis [1], an anodic oxidation, carboxylic acids are able to form dimers through precent decarboxylation and generation of radicals. The scope of the Kolbe reaction can be considerably enhanced by cross-reaction of two different carboxylic acids. L-glutamic acid (Glu), which is blocked at the α-carboxyl and the amino group by protective groups, opens a new way for the synthesis of non-proteinogenic amino acids with defined stereochemistry. As examples Z-L-norleucine and amino acids containing a second amino group at its side chain were synthesized.