Fmoc-aza-β3-Lys-OAllyl and Fmoc-aza-β3-Asp-OAllyl for on-resin head-to-tail cyclization of aza-β3-peptides

A rapid and efficient Fmoc/t-Bu solid-phase peptide synthesis (SPPS) of cyclic aza-β3-peptide analogs by allyl strategy is described. Our synthetic approach includes the synthesis of two new aza-β3-amino acids, Fmoc-aza-β3-Lys-OAllyl and Fmoc-aza-β3-Asp-OAllyl, then the resin attachment of the first aza-β3-amino acid via its side chain, successful use of combination of three orthogonal removable protecting groups, stepwise solid-phase synthesis of linear peptide analog, and on-resin head-to-tail cyclization.