Conformational studies on a medium size cyclopseudopeptide containing the oxazolidin‐2‐one moiety

Abstract

An efficient synthesis of a 24 pseudopeptide membered ring in solution is reported in good yield. The cycle contains four units, all formed by an a-amino acid (Xaa) and a 4-carboxy-5-methyl-oxazolidin-2-one group (4-carboxy-5-methyl- oxazolidin-2-one = Oxd) in the same configuration (L or D). In the final sequence, the four LL or DD units are alternated so that, after cyclization, cyclo-(L-Xaa-L-Oxd-D-Xaa-D-Oxd-L-Xaa-L-Oxd-D-Xaa-D-Oxd) is formed. The conformational analysis of this compound has been performed by means of infrared and 1H NMR spectroscopy and shows that the CHa hydrogens of the a-amino acids retain the very deshielded chemical shifts recorded in the spectra of the free precursors. Furthermore, the NH hydrogen have a weak tendency to form cross peaks, thus suggesting that the cycle lies in a large circle able to host small molecules, thus this compound is a promising candidate for drug delivery studies. Copyright © 2012 John Wiley & Sons, Ltd

Synthetic Receptors Based on Abiotic Cyclo(pseudo)peptides

“…These compounds were, however, mainly studied with regard to their membrane transport and self-assembly properties. Cyclic pseudopeptides with alternating natural α-amino acid and oxazolidin-2-one residues have also been described [65], and although acyclic pseudopeptides containing these building blocks have been shown to assemble into fibers and gels [66], little is known about the binding properties of the cyclic counterparts. Ranganathan and Karle prepared cyclic pseudopeptides containing adamantane residues or used the OH group in the side chains of serine or tyrosine to prepare cyclic depsipeptides [52].…”