After establishing the synthesis of peptide-EBXs, we explored their applications in different reactions. Among the most robust reactions for EBX reagents are the alkynylation and alkenylation of thiols (Fig ). In an organic solvent, protected Cys was incorporated efficiently to give thioalkynes 5a-d. Alternatively, 5a can also be obtained in 34% yield in a one-pot procedure from peptide 2c bypassing the isolation of the peptide-EBXs. One-pot amidation with 1b followed by reaction with protected cysteine gave 5a in 34% isolated yield.