One‐pot peptide cleavage and macrocyclization through direct amidation using triazabicyclodecene

Abstract

AbstractWe have developed a novel protocol for a one‐pot cleavage from solid support and subsequent cyclization to form small macrocyclic peptides. Synthesized on a 4‐hydroxymethyl benzamide (HMBA) resin, the peptides are cleaved from the solid support through a 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) assisted acyl transfer reaction. The resulting linear peptides then undergo an intramolecular cyclization, presumably upon in situ attack of the N‐terminal amine on the TBD‐activated ester. This protocol requires catalytic quantities of TBD and eliminates the need for orthogonal side chain deprotection strategies and ether trituration/work‐up steps, streamlining the synthesis of head‐to‐tail macrocyclic peptides.