Conformational studies of the linear homooligomers of a glucose-derived furanoid sugar amino acid

Conformational analysis of the linear tetramer of the glucose-derived furanoid sugar amino acid 1 by NMR and constrained molecular dynamics studies revealed that the fully protected tetramer 2a has a well-defined structure in CDCl3 with repeating β-turns, each involving a 10-membered ring structure with intramolecular hydrogen bonds between NHi → COi−2. Its deprotected versions 2b and 2c showed aggregation in organic solvents with structures similar to that of 2a.