Handles for Fmoc solid-phase synthesis of protected peptides.

Protected peptide fragments are valuable building blocks for the assembly of large peptide sequences through fragment condensation approaches, whereas protected peptides are typically synthesized for the preparation of amide-bridge cyclic peptides in solution. Efficient synthesis of both protected peptides and protected peptide fragments by solid-phase peptide synthesis methodology requires handles that attach the growing peptides to the polymeric support and can be cleaved under appropriate conditions, while maintaining intact the side-chain protecting groups. Here, we provide an overview of attachment methods described in the literature for the preparation of protected peptides using Fmoc/tBu chemistry, including the most commonly used acid-labile linkers along with the most recent and sophisticated.