NMR‐spektroskopische Untersuchungen zum Konformations‐verhalten von 2′‐ und 3′‐halogensubstituierten Pyrimidinnucleosiden

Abstract

N.M.R. Spectroscopical Investigations on the Conformational Behaviour of Some 2′ ‐ and 3′‐Halogen‐substituted Pyrimidine Nucleosides A series of 2′‐ and 3′‐halogenated pyrimidine nucleosides has been synthesized and investigated by 1 H, 13 C and 19 F n.m.r. spectroscopy. The 1 H and 13 C chemical shifts for the positions 2′ and 3′ depend linearly but oppositely on the substituent electronegativities X R . The conformational equilibrium N ⇌ S of the nucleosides in solution is determined. An approximately linear correlation between the prefered gauche‐gauche interaction of the exocyclic CH 2 OH groups and the ribose N conformation has been found.