12 research outputs found
Effects of Thionation and Fluorination on Cis–Trans Isomerization in Tertiary Amides: An Investigation of <i>N</i>‑Alkylglycine (Peptoid) Rotamers
Peptoids
constitute a class of peptidomimetics with potential as
protease resistant, biologically active ligands. To harness the full
potential of such compounds, however, detailed predictive insight
into their propensity to adopt well-defined secondary structures is
highly desirable. In this work we present an investigation of the
effects of thioamides and/or fluorides in peptoid monomer model systems
using chemical synthesis, NMR spectroscopy, and X-ray crystallography.
We find that the steric environment surrounding the tertiary amide
bonds is the key promoter of conformational preference, and X-ray
crystallographic interrogation of our model systems did not suggest
the presence of stabilizing <i>n</i> → π* interactions
unless the carbonyls were altered electronically by α-halogenation
or thioamide formation. In addition to the function as an investigative
tool, these two types of modification may thus be utilized as stabilizers
of secondary structure in future oligomer designs, such as the <i>cis-</i>amide-based polypeptoid helices that resemble the polyproline
type-I helix