ISSN:
0749-1581
Keywords:
13C NMR
;
1H NMR
;
4,9-Dihetero-(Z,Z)-cyclodeca-1,6-dienes
;
Ring inversion barriers
;
Restricted rotation
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The dynamic 1H and 13C 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.
Additional Material:
4 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260280713
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