Esters in peptide synthesis

Patent Pending For coupling the peptides the carboxyl group is usually activated. This is important for speeding up the reaction. There are two main types of activating groups: carbodiimides and triazolols. However the use of pentafluorophenyl esters (FDPP,[12] PFPOH[13]) and BOP-Cl[14] are useful for cyclising peptides.