Synthesis and application of a novel coupling reagent, ethyl 1-hydroxy-1H -1,2,3-triazole-4-carboxylate

An optimal coupling reagent, ethyl 1-hydroxy-1H-1,2,3-triazole-4-carboxylate (HOCt), has been designed and synthesised for application to solid phase peptide synthesis using Fmoc chemistry. It is used in combination with carbodiimide reagents, has very high coupling efficiency, and does not absorb at 302nm, thus allowing real-time monitoring of each coupling cycle. Its applications in the synthesis of endothelin analogues and difficult sequences are also discussed.