Synthesis of a cyclic pseudo 310 helical structure from a β-amino acid-l-proline derived tripeptide via a ring closing metathesis reaction

The combination of homo-phenylglycine (Hpg) and proline leads to the formation of a β-turn mimic, which can be transformed into a cyclic peptide using a ring closing metathesis reaction. The presence of the pentenoyl and allyl groups at the terminus of the peptide leads to the concomitant formation of a linker surrogate fourth amino acid (6-amino-4-hexenoic acid; Aha) during the cyclization. The cyclic peptide is unique in having a pseudo 310 helical structure.