Induced axial chirality in the biphenyl core of the proatropoisomeric, C alpha-tetrasubstituted alpha-amino acid residue Bip in peptides

Chemistry. 2005 Nov 18;11(23):6921-9. doi: 10.1002/chem.200500187.

Abstract

An induced axial chirality in the biphenyl core of the 2',1':1,2;1'',2'':3,4-dibenzcyclohepta-1,3-diene-6-amino-6-carboxylic acid (Bip) residue, a conformationally labile, atropoisomeric, C(alpha)-tetrasubstituted alpha-amino acid, was observed by CD and (1)H NMR spectroscopic techniques in the linear dipeptides Boc-Bip-Xaa*-OMe where Boc=tert-butoxycarbonyl, OMe=methoxy, and Xaa*=D- and/or L-Ala, -Val, -Leu, -Phe, -(alphaMe)Val and -(alphaMe)Leu. Chiral induction was significantly lower in the isomeric dipeptides Boc-Xaa*-Bip-OMe, with the Xaa* residue located at the N-terminus of Bip, as well as in the cyclic dipeptide cyclo-[Bip-L-Ala]. The results obtained in solution were confirmed by X-ray diffraction analysis of a crystalline sample of Boc-(R)-Bip-D-Ala-OMe.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / chemistry*
  • Circular Dichroism
  • Crystallography, X-Ray
  • Nuclear Magnetic Resonance, Biomolecular
  • Peptides / chemistry*
  • Stereoisomerism

Substances

  • Amino Acids
  • Peptides