Spontaneous Self-Assembly of Fully Protected Ester 1:1 [α/α-Nα-Bn-hydrazino] Pseudodipeptides into a Twisted Parallel ß-Sheet in the Crystal State.
J Org Chem
; 81(19): 9037-9045, 2016 10 07.
Article
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| MEDLINE
| ID: mdl-27627436
ABSTRACT
Previous studies have demonstrated that amidic α/ß-pseudodipeptides, 11 [α/α-Nα-Bn-hydrazino], have the ability to fold via a succession of γ-turn (C7 pseudocycle) and hydrazinoturn in CDCl3 solution, their amide terminals enabling the formation of an intramolecular H-bond network. Despite their lack of a primary amide terminals allowing the formation of the hydrazinoturn, their ester counterparts 1-4 were proven to self-assemble into C6 and C7 pseudocycles by intramolecular H-bonds in solution state and into an uncommon twisted parallel ß-sheet through intermolecular H-bonding in the crystal state to form a supramolecular helix, with eight molecules needed to complete a full 360° rotation. Such self-organization (with eight molecules) has only been observed in a specific α/α-pseudodipeptide, depsipeptide (Boc-Leu-Lac-OEt). Relying on IR absorption, NMR, X-ray diffraction, and CD analyses, the aim of this study was to demonstrate that stereoisomers of ester 11 [α/α-Nα-Bn-hydrazino] pseudodipeptides 1-4 are able to self-assemble into this ß-helical structure. The absolute configuration of the asymmetric Cα-atom of the α-amino acid residue influences the left- or right-handed twist without changing the pitch of the formed helix.
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Banco de datos:
MEDLINE
Asunto principal:
Dipéptidos
/
Hidrazinas
Idioma:
En
Revista:
J Org Chem
Año:
2016
Tipo del documento:
Article
País de afiliación:
Francia