Total Synthesis of Cyclic Octapeptide Reniochalistatin E

The total synthesis of a naturally occurring proline-enriched cyclic octapeptide, reniochalistatin E, from a marine sponge, where all the amino acids have the L-configuration, was reported. The reniochalistatin E was synthesized by applying a two-step solid-phase/solution synthesis strategy. The linear octapeptide was assembled by standard Fmoc chemistry on the solid phase, and subsequently cyclization was achieved by a solution method. The final product was purified by a preparative RP-HPLC system, and its structure was identified by HR-QTOF-MS, and 1 H and 13 C NMR.