Topologically Diverse Shapes Accessible by Modular Design of Arylopeptoid Macrocycles.

N-Substituted aromatic cyclooligoamides composed of different combinations of ortho-, meta-, and/or para-arylopeptoid residues carrying methoxyethyl side chains have been efficiently synthesized by macrocyclization of the corresponding linear oligomers. The study of the architectures of these macrocycles in solution and solid state has revealed that tetracyclic arylopeptoids adopt sequence-dependent shapes with different backbone amide conformations and side-chain orientations. Remarkably, despite the absence of intramolecular H-bonding ability, some of these arylopeptoid macrocycles show well-defined architectures in solution.