Premium
Conformational study of the 4,9‐dihetero‐( Z,Z )‐cyclodeca‐1,6‐diene ring system; the mono‐ and di‐benzo analogues
Author(s) -
Kleinpeter E.,
Hartmann J.,
Schroth W.
Publication year - 1990
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260280713
Subject(s) - chemistry , conformational isomerism , intramolecular force , heteroatom , ring (chemistry) , ring flip , double bond , stereochemistry , crystallography , computational chemistry , molecule , organic chemistry , polymer chemistry
The dynamic 1 H and 13 C NMR spectra of a series of mono‐ and bis‐annelated 4,9‐dihetero‐( Z,Z )‐cyclodeca‐1,6‐dienes were obtained and are discussed with respect to ground‐state conformers and the barriers to ring inversion, and to the restricted rotation about exocyclic partial C,N double bonds. The ten‐membered rings are, with one exception, anancomeric chair conformers and interconvert via a combination of single bond rotations and bond angle bendings. Depending on the heteroatoms present, the series of decreasing barriers to ring inversion S > NH > O was obtained. Benzannelation decreases the free energy of activation of the same dynamic process owing to greater intramolecular transannular H,H interactions.