ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
In view of the chemical and structural interest of cyclopeptides bearing an electron withdrawing substituent directly bonded at the amide nitrogen atom, the two N-p-toluensulfonyl (N-tosyl) derivatives cyclo[-Phe(Tos)-D-Phe-] (I) and cyclo[-Phe(Tos)-D-Pro-] (II) have been synthesized and their stereochemistry defined. The molecular structure of I, as determined by x-ray diffraction analysis, is reported together with 1H-nmr parameters indicating the preferred rotameric conformation in chloroform solution. The N-tosyl group alters the geometry of the cyclodipeptide ring by lengthening both the N—C bonds departing from the tosylated nitrogen and reducing the corresponding ring angle. The 6-membered peptide ring adopts an unusual “sofa” conformation with the Tos-Phe Cα atom deviating 0.230(3) Å out of the mean plane of the other five ring atoms. One of the two S—O bonds forms a planar system that involves the tosylated nitrogen and the corresponding amide carbonyl. In the crystal, both the benzylic side chains are folded over the heterocyclic ring, whereas in chloroform solution, the benzylic side chain of the D-Phe prefers an extended conformation.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360280117
Permalink
