Macrocyclic Peptide Synthesis

Significance

The synthesis of novel macrocyclic peptides containing Pro-Gly sequences was achieved by exploiting oligomerization/cyclization/cleavage sequential reactions on an oxime resin 1. Thus, the liner peptide sequence 5 (resin loading: 0.3 mmol/g) was prepared from 1 and Boc-Ala-OH via the standard solid-phase peptide synthetic method. The removal of the Boc group, followed by the oligomerization/cyclization/cleavage reaction with DIPEA in DMF, afforded cyclic peptides 6a-c in 51% (6a/6b/6c = 91:8:1). The methodology was applied to the three linear sequences of six to eight amino acids containing a Pro-Gly-Pro-Gly unit to give nine novel large macrocyclic peptides.