Ribosomal incorporation of <i>N</i> -acetyl-3,5-bis(chloromethyl)benzylthio- <scp>l</scp> -alanine for developing an mRNA-displayed bicyclic peptide library cyclized <i>via</i> 1,3,5-tris(methyl)benzene

We report a novel method for constructing an mRNA-displayed bicyclic peptide library cyclized through 1,3,5-tris(methyl)benzene by ribosomally incorporating <i>N</i>-acetyl-3,5-bis(chloromethyl)benzylthio-L-alanine, enabling the selection of bicyclic peptides against specific targets. Using this method, we successfully identified bicyclic peptides that bind to human Trop2 and VEGF165, providing a new strategy for selecting bicyclic peptides cyclized by trimethylbenzene.