Recent Advances in Ynamide Coupling Reagent

Abstract

Coupling or condensation reagents are compounds that can be used to promote the direct condensation of carboxylic acids with amines or alcohols to furnish amide or ester bond, respectively. Since their discovery, coupling reagents have been widely used in the manufacture of drugs, materials, cosmetics and other fine chemicals containing amide or ester bond. In particular, coupling reagent plays a crucial role in the chemical synthesis of peptides which involves the iterative amide bond formation between proteinogenic α-amino acids. However, current peptide synthesis methods and strategies are mainly relied on the reagents and techniques developed in 1950~1980s, and are reaching a high standard and their inherent limits. For example, the impurities and racemization/epmimerization caused by over activation of conventional coupling reagents have become major concerns of peptide drug manufacture. Moreover, the poor atom economy of the solid phase peptide synthesis results in large amount of chemical waste, and thus posing formidable challenge to the sustainable development. Only disruptive innovations involving new reagents and novel condensation mechanism can solve the notorious issues that plague current peptide synthesis. In this context, our research group disclosed that ynamide could be used as a novel coupling reagent to promote amide and ester bond formation via the condensation of carboxylic acids with amines or alcohols. More importantly, ynamide coupling reagents could also be used for peptide bond formation in a racemization free manner. Herein, the discovery as well as the application of ynamide coupling reagent in the construction of amide and ester bonds is systematically summarized.