Oligo(cyclohexylidene) oximes and derivatives as probe molecules for long-range substituent effects on 13C NMR chemical shifts

Autor:	Frans J. Hoogesteger, Bart A. J. Jansen, Theodorus J. M. de Bruin, Leonardus W. Jenneskens, David M. Grove
Rok vydání:	1996
Předmět:	chemistry.chemical_classification Double bond Chemical shift Substituent chemistry.chemical_element Carbon-13 NMR Photochemistry Oxime Medicinal chemistry chemistry.chemical_compound chemistry Molecule Carbon Two-dimensional nuclear magnetic resonance spectroscopy
Zdroj:	Journal of the Chemical Society, Perkin Transactions 2. :2327
ISSN:	1364-5471 0300-9580
DOI:	10.1039/p29960002327
Popis:	For a series of rodlike aliphatic oximes (1–4) the influence of the oxime substituent on the 13C NMR chemical shifts has been studied. Various 2D NMR techniques were applied for the unequivocal assignment of their 1H and 13C resonances. For bicyclohexylidene oximes 1–2 long-range substituent effects on the 13C NMR chemical shifts of aliphatic carbon atoms of the six-membered rings due to the presence of the oxime group are discernible up to positions six carbon–carbon bonds distant from the iminyl carbon! The 13C NMR data obtained for bicyclohexyl oximes 3–4 reveal that in this series the effect is limited to carbon atoms which are five bonds distant from the iminyl carbon. The observed differences between the two series is attributed to the presence of an olefinic double bond in 1–2, which becomes polarized by the electric field of the oxime substituent.
Databáze:	OpenAIRE
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