ISSN:
0749-1581
Schlagwort(e):
Conformation
;
π-Bond polarization
;
Force field calculations
;
HMQC
;
HMBC
;
Push-pull alkenes
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The 1H and 13C NMR spectra of a variety of differently 2,5,6-trisubstituted 3,4-dihydro-4-oxo-2H-thiins (integrated push-pull alkenes) were unequivocally assigned by means of a wide variety of 1D and 2D NMR spectroscopic methods. The NMR parameters thus obtained, together with the results of accompanying force-field calculations, proved useful in determining the preferred ring conformation of 3,4-dihydro-4-oxo-2H-thiin (half-chair). Additionally, the 13C chemical shift difference, Δδ(C-5, C-6), could be employed to indicate the degree of bond polarization of the partial C-5—C-6 double bond (push-pull character); the barrier to rotation, otherwise used to estimate this parameter characterizing the push-pull alkenes, cannot be applied owing to the ring fusion. Interestingly, NH2 proved less effective in C-5—C-6 bond polarization than NHPh.
Zusätzliches Material:
3 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/mrc.1260320808
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