Synthesis of the cyclic heptapeptide axinellin A

The first synthesis of the naturally occurring cyclic peptide axinellin A has been achieved. Cyclization and subsequent deprotection of linear precursors containing either a t-butyl protected Thr residue or a Thr(Psi(Me,Me)pro) derivative gave a cyclic peptide, identical in all respects to the naturally occurring material, with the exception that the synthetic peptide does not exhibit the cytotoxic activity reported for the natural product. (C) 2009 Elsevier Ltd. All rights reserved.