10.1021/acs.joc.8b00349.s005 Yukiko Tojo Yukiko Tojo Ko Urushibara Ko Urushibara Sawori Yamamoto Sawori Yamamoto Hirotoshi Mori Hirotoshi Mori Hyuma Masu Hyuma Masu Mayumi Kudo Mayumi Kudo Tomoya Hirano Tomoya Hirano Isao Azumaya Isao Azumaya Hiroyuki Kagechika Hiroyuki Kagechika Aya Tanatani Aya Tanatani Conformational Properties of Aromatic Oligoamides Bearing Pyrrole Rings American Chemical Society 2018 amide carbonyl lone-pair electrons preference Aromatic Oligoamides Bearing Pyrrole Rings N pyrrole π electrons amide bond methylated amides ci 5- membered N 2018-03-29 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Conformational_Properties_of_Aromatic_Oligoamides_Bearing_Pyrrole_Rings/6130895 <i>N-</i>Alkylbenzanilides generally exist in cis conformation both in the crystalline state and in various solvents, and this cis conformational preference can be utilized to construct dynamic helical oligoamides. Here, we synthesized the pyrrole-containing amides <b>2</b>–<b>5</b> and their oligomers <b>6</b>–<b>8</b> and examined their conformations in the crystalline state and in solution. All the <i>N</i>-methylated amides showed cis conformational preference in solution, but the ratio of the cis isomer was decreased when the amide bond was attached at the 4-position of the pyrrole ring, probably because the destabilization of the trans conformer due to electronic repulsion between the pyrrole π electrons and the amide carbonyl lone-pair electrons is reduced due to the small torsion angle between the 5-membered <i>N</i>-pyrrole and the amide bond. In the crystalline state, <i>N</i>-methylated amides showed cis structure, except for compound <b>5</b>, and cis conformational preference was observed for the pyrrole amides. The CD spectra of oligoamides <b>15</b>–<b>18</b> bearing chiral <i>N</i>-substituents were consistent with the presence of dynamic and well-defined chiral foldamers, which were structurally distinct from <i>N</i>-alkylated poly­(<i>p</i>-benzamide)­s <b>1</b>.