Synthesis of a Novel cis-Proline-Derived Cyclic Type VI β-Turn Mimic via Ring-Closing Metathesis.

A cis-proline derived cyclic mimic of a type VI β-turn is synthesized via a ring-closing metathesis reaction. The solution NMR conformational study indicates that the major conformer of the cyclic peptide adopts a type VIa β-turn in CDCl3 and a type VIb β-turn in DMSO-d6.