Sulfur-Controlled Modulation of Peptoid Atropisomeric Foldamers

We incorporated the hetero atoms (O/S) at the ortho-position to investigate the steric influence on controlling the rotational barrier around the C-N chiral axis and to elucidate the chiral attributes of sulfur-containing <i>N</i>-aryl peptoids. This study reports the simultaneous installation of a C-N chiral axis and the integration of sulfur-containing stereogenic elements in peptoid atropisomeric foldamers. By leveraging multiple chiral elements in peptoids, we demonstrated subtle structural variations, particularly by varying the sulfur oxidation states, that can lead to significant differences in the rotational energy barrier, as determined by dynamic HPLC. Additionally, we employed single-crystal X-ray crystallography to elucidate local conformational ordering and computational studies to identify noncovalent interactions in this class of atropisomers. Through these combined approaches, we explored sulfur-controlled modulation of <i>N</i>-aryl peptoid atropisomeric foldamers.