Induced axial chirality in the biphenyl core of the proatropoisomeric, C alpha-tetrasubstituted alpha-amino acid residue Bip in peptides.
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.
Mazaleyrat
Jean-Paul
JP
SIRCOB, UMR CNRS 8086, University of Versailles, 78035 Versailles, France.
Wright
Karen
K
Gaucher
Anne
A
Toulemonde
Nathalie
N
Dutot
Laurence
L
Wakselman
Michel
M
Broxterman
Quirinus B
QB
Kaptein
Bernard
B
Oancea
Simona
S
Peggion
Cristina
C
Crisma
Marco
M
Formaggio
Fernando
F
Toniolo
Claudio
C
D000596:Amino Acids / Q000737:chemistry*; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry*; D013237:Stereoisomerism
D000596:Amino Acids; D010455:Peptides