Open AccessOn the conformation of 5-substituted uridines as studied by proton magnetic resonance
Author(s) -
Wolfgang Uhl,
Josef Reiner,
Hans Günter Gassen
Publication year - 1983
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/11.4.1167
Subject(s) - conformational isomerism , proton magnetic resonance , alkane stereochemistry , stereochemistry , proton , resonance (particle physics) , crystallography , nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , chemistry , molecule , crystal structure , organic chemistry , physics , quantum mechanics , particle physics
The proton magnetic resonance (pmr) spectra of 10 basemodified uridine derivatives x5Urd have been measured at 3 degrees, 30 degrees, and 60 degrees C in order to correlate the electronic effects of different substituents with the molecular conformation of the respective nucleosides. The results presented demonstrate the close relation between conformational parameters and the electron-affinity of the substituents as reflected by their Hammett constants. Going from electron-donating to electron-accepting groups, the portion of N-conformer in the ribose N in equilibrium S equilibrium increases from 44% to about 90%. In addition the percentage of gauche-gauche rotamer as measured for the exocyclic groups changes from about 30% in nh52Urd to more than 80% in no52Urd.