Conformational preferences in the β-peptide oligomers of cis-2-amino-1-fluorocyclobutane-1-carboxylic acid. (17th December 2014)

• Record Type: Journal Article
• Authors: Hassoun, Ammar; Grison, Claire M.; Guillot, Régis; Boddaert, Thomas; Aitken, David J.
• Is Part Of: New journal of chemistry. Volume 39:Number 5(2015:May)
• Page Start: 3270
• Page End: 3279
• Publication Date: 2014-12-17
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c4nj01929f
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : These oligomers adopt a regular zig-zag strand-like secondary structure which does not rely on intra-residue 6-ring hydrogen bonds for stability. Abstract : An efficient synthesis of cis -2-amino-1-fluorocyclobutane-1-carboxylic acid in single enantiomer form was established and protected homo-oligomers (2-, 4-, and 6-mers) of this cyclic cis -β-amino acid were prepared. Conformational analysis of these oligomers using IR, NMR and CD techniques in solution, supported by molecular modelling studies, suggested a strong conformational preference for a well-defined strand-like structure in which intra-residue hydrogen bonding is weak at best and is not consequential for adoption of the secondary structure. Single crystal X-ray analysis of the tetramer showed that a regular strand-like conformation is adopted in the solid state; only intermolecular hydrogen bonding networks are observed. The backbone topology and the 4-membered ring orientations are noticeably different from those of the tetramer of the corresponding non-fluorinated cis -β-amino acid.