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Chiral α-Aminoxy Acid/Achiral Cyclopropane α-Aminoxy Acid Unit as a Building Block for Constructing the α N-O Helix.
- Source :
-
Journal of Organic Chemistry . 7/16/2010, Vol. 75 Issue 14, p4796-4805. 10p. - Publication Year :
- 2010
-
Abstract
- The monomer 1 derived from achiral 1-(aminoxy)cyclopropanecarboxylic acid (OAcc) and oligopeptides 2-9 consisting of a chiral α-aminoxy acid and an achiral α-aminoxy acid such as OAcc were synthesized and their structures characterized. The eight-membered-ring intramolecular hydrogen bond, namely the α N-O turn, was formed between adjacent residues independent of their chirality. However, the helix formation was sequence-dependent. Dipeptide 2 bearing chiral α-aminoxy acid (D-OAA) at the N-terminus and achiral OAcc at the C-terminus preferentially adopted a right-handed 1.88 helical structure, but dipeptide 3 (OAcc-D-OAA) did not. Theoretical calculation results, in good agreement with experimental ones, revealed that the biased handedness of α N-O turn found in OAcc residue depends on its preceding chiral residue. It was then found that the helical conformation was destroyed in the case of oligopeptides 6 and 7 [OAA-(OAcc)n, n = 2, 3]. The crystal structure of tripeptide 8 (iPrCO-D-OVal-OAcc-D-OVal-NHiBu) further disclosed the helical structure formed by three consecutive homochiral α N-O turns. This study has uncovered achiral aminoxy acid residues such as the OAcc unit as a useful building block to be incorporated into chiral aminoxy peptides to mimic chiral helix structure. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00223263
- Volume :
- 75
- Issue :
- 14
- Database :
- Academic Search Index
- Journal :
- Journal of Organic Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 52349352
- Full Text :
- https://doi.org/10.1021/jo100810m