Ynamide: A New Coupling Reagent for Amide and Peptide Synthesis

The discovery and application of ynamide coupling reagents is highlighted with a brief summary of the development history of coupling reagents in amide and peptide synthesis. As novel coupling reagents, ynamides are not only effective for simple amide and dipeptide synthesis but also can be used for peptide fragment condensation. More importantly, no racemization was detected during the activation of α-chiral carboxylic acids by employing ynamide coupling reagents. 1 Introduction 2 Carbodiimide Coupling Reagents 3 Uronium/Guanidinium Salt Coupling Reagents 4 Phosphonium Salt Coupling Reagents 5 Ethoxyacetylene as a Coupling Reagent 6 Ynamine Coupling Reagents 7 Ynamide Coupling Reagents 8 Summary and Outlook