Vinyl esters have been generated from carboxylic acid addition to different acetylene derivatives and employed in amide bond formation. Since pioneering studies in the 1950s by Arens, alkoxyacetylenes have served as activating agents for peptide coupling. Moreover, racemization-free ruthenium-catalyzed addition of protected dipeptides to alkynes gave the corresponding C-terminal peptide enol esters which were employed in enzyme-catalysed fragment couplings. Inherent challenges in the use of vinyl esters are due in part to the reactivity of the alkyne precursor and the acyl enol ether counterpart in the activation and amino acylation steps, respectively. Innovations from the Zhao lab have overcome such challenges through the respective uses of allenones and ynamides as activating agents in peptide coupling with minimal racemization. For example, 1-phenylbuta-2,3-dien-1-one (65) was used in the N-to C-solution-phase synthesis of the proteasome inhibitor Carfilzomib (73, Scheme 8). Amino acyl activation was typically performed with enone 65 at room temperature in dichloroethane to form the vinyl esters (e.g., 67) which were isolated by chromatography and subsequently coupled to the respective tert-butyl amino ester at room temperature in DMF.