2-Chloroimidazolium Chloride as a Coupling Reagent for Amide Bond Formation

A highly efficient synthesis strategy, focusing on amide bond formation and peptide synthesis, has been developed under mild condition by employing a 2-chloroimidazolium chloride IMesCl-Cl as a coupling reagent. This strategy exhibited wide substrate scope and good chemo-selectivity. Notably, no significant loss of enantiopurity was observed when employing this strategy to dipeptide synthesis. This method was also successfully applied in glycine-conjugate bile acids synthesis. A plausible formation mechanism via an active ester intermediate was proposed.