Helical Structures of Nylon‐Like Oligomers Consisting of 1,2‐Diamine and 1,2‐Dicarboxylic Acid Building Blocks Containing a Five‐Membered Ring Constraint

A series of nylon‐like oligomers was synthesized, which consisted of alternating cyclic 1,2‐diamine and 1,2‐dicarboxylic acid building blocks with a five‐membered ring constraint. The nylon 2 4 oligomers are symmetric and display helical structures similar to the β‐peptide 12‐helix with intramolecular 12‐membered ring hydrogen bonds. The cyclopentane moiety allows each building block to promote 12‐helical folding. In addition, a tartaric acid derivative with the acetonide moiety increases the solubility of oligomers in common organic solvents and promotes helical folding. Nylon folds: Helical oligomers related to nylon 2 4 were synthesized from 1,2‐diamine and 1,2‐dicarboxylic acid building blocks. The oligoamide backbone is equivalent to a β‐peptide backbone with the same length in terms of the number of amide groups. A five‐membered ring constraint in each subunit promotes helical folding similar to the β‐peptide 12‐helix.