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Conformational studies of oligomeric oxetane‐based dipeptide isosteres derived from L ‐rhamnose or D ‐xylose
Author(s) -
Johnson Stephen W.,
Jenkinson née Barker Sarah F.,
PérezVictoria Ignacio,
Edwards Alison A.,
Claridge Timothy D. W.,
Tranter George E.,
Fleet George W. J.,
Jones John H.
Publication year - 2005
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/psc.658
Subject(s) - chemistry , oxetane , dimer , monomer , dipeptide , chloroform , stereochemistry , intramolecular force , oligomer , nuclear magnetic resonance spectroscopy , trimer , steric effects , circular dichroism , peptide , polymer chemistry , polymer , organic chemistry , biochemistry
Conformational investigations have been undertaken on oligomers (dimers, tetramers, hexamers) of five closely related oxetane‐based dipeptide isosteres. All the oligomers were subjected to a range of studies by NMR, FT‐IR and CD spectroscopy. The oligomers derived from methyl 2,4‐anhydro‐5‐azido‐3‐ O ‐ tert ‐butyldimethylsilyl‐5‐deoxy‐ L ‐rhamnonate ‘monomer’ all exhibited evidence of ordered conformations in chloroform and 2,2,2‐trifluoroethanol (TFE) solution. 5‐Acetamido and N ‐methylamide derivatives of the L ‐rhamnonate ‘monomer’, along with a ‘dimer’ lacking silyl protection at C‐3, were synthesized to ascertain the role of intramolecular interactions. This led to the conclusion that, for the L ‐rhamnonate oligomers, steric interactions govern the conformational preference observed. The equivalent silyl‐protected D ‐lyxonate oligomers gave ordered CD spectra in TFE solution, but NMR and FT‐IR spectroscopy in chloroform solution suggested an irregular, non‐hydrogen bonded system. The remaining silyl‐protected 6‐deoxy‐ L ‐altronate, 6‐deoxy‐ D ‐gulonate and D ‐fuconate oligomers appear to be characterized by their lack of ordered conformation in TFE and chloroform solution. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd.