ISSN:
0030-4921
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Vicinal C,H spin coupling (3JC,H) in substituted alkenes has been investigated systematically. Emphasis is laid on the stereochemical significance (Jtrans/Jcis) and on the various structural factors which influence 3JC,H, such as π-bond order, torsional angle φ, bond angle θ, electronegativity of substituents and steric effects. A new type of γ-effect is observed in 3JtransC,H which appears to have the same origin as the γ-shift effect. By comparison of 3JCH3,H and 3JH,H, it was found that the relation 3JC,H ≍ 0·6 3JH,H holds for both trans and cis coupling constants. Finally, it is concluded that 3JC,H constitutes a valuable criterion to distinguish E- and Z-isomers, particularly in trisubstituted alkenes. Applications to natural products are presented.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1270071213
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