Conformationally Constrained Aliphatic−Aromatic Amino-Acid-Conjugated Hybrid Foldamers with Periodic β-Turn Motifs

In this note, we describe the design, synthesis, and structural
studies of novel hybrid foldamers derived from Aib-Pro-Adb building blocks that display repeat β-turn structure
motif. The foldamer having a conformationally constrained
aliphatic−aromatic amino acid conjugate adopts a well-defined, compact, three-dimensional structure, governed by
a combined conformational restriction imposed by the
individual amino acids with which it is made of. Conformational investigations by single-crystal X-ray and solution-state NMR studies were undertaken to investigate the
conformational preference of these foldamers with a hetero-backbone. Our findings suggest that constrained aliphatic−aromatic amino acid conjugates would offer new avenues
for the de novo design of hybrid foldamers with distinctive
structural architectures.