ISSN:
1434-4475
Schlagwort(e):
Bilatrienes-abc
;
2,3-Dihydrobilatrienes-abc
;
13C-NMR
;
Phytochrome models
;
Tautomerism
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract By investigation of bilatrienes-abc possessing a rigid tautomeric structure within their pyrromethene fragment, using13C-NMR spectroscopy, a criterion for the fixation of tautomerism was deduced: if there is a signal in the otherwise unoccupied shift region between 157 and 170 ppm corresponding to an azomethine fragment, tautomerism is fixed. If there is no signal in this region there is a rapidly equilibrating system of the two possible tautomers. This criterion may be used as well for natural substitution patterns. Moreover, assignment of the13C-signals by correlation with the easily assigned1H-NMR signals establishes the position of the fixed tautomeric system. The criterion is applied as well to the 2,3-dihydrobilatrienes-abc where it is in accord with the results gained from a coupling criterion reported earlier.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00798279
