1,2,3-Triazoles in Peptidomimetic Chemistry

The ability to synthesise small peptidomimetics that mimic the secondary structure of proteins is an ever expanding area of research directed at sourcing new medicinal agents and biological probes. A significant current challenge is to mimic protein epitopes under physiological conditions using small peptidomimetics that are easy to prepare. The copper- and ruthenium-catalysed Huisgen cycloaddition reactions provide such a general synthetic method, with the resulting 1,2,3-triazoles being good peptide bond mimics. The ability to prepare both 1,4- and 1,5-substituted 1,2,3-triazoles under these chemically benign conditions provides both linear and bent peptidomimetics. Examples of the use of 1,2,3-triazoles to define the geometry and properties of a peptidomimetic abound. This review highlights such successes but also describes a number of failures in order to guide and inspire future efforts of chemists in this area.