Novel Aryl Boronate Ester Based Amino Acids as Orthogonal Building Blocks for Fmoc Solid Phase Peptide Synthesis

Three novel aryl boronate ester based amino acids are described. These useful building blocks were found to exhibit all of the chemical properties compatible to the Fmoc strategy solid-phase peptide synthesis and orthogonal to Boc, tBu, Pbf and Trt groups. Their effective application for synthesis of different types of peptidomimetics has been demonstrated by high-quality preparation of lipidated peptide MP-196 C-C8, on-resin head-to-tail cyclization of desotamide B and lactam bridging of hPTHrP-(11-19) through a facile and metal-free procedure by standard Fmoc-assisted solid-phase peptide synthesis.