- Oligo(cyclohexylidene) oximes and derivatives as probe molecules for long-range substituent effects on13C NMR chemical shifts
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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, whch becomes polarized by the electric field of the oxime substituent.
- Hoogesteger, Frans J.,Grove, David M.,Jenneskens, Leonardas W.,De Bruin, Theodorus J. M.,Jansen, Bart A. J.
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p. 2327 - 2334
(2007/10/03)
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- Synthesis of tercyclohexanones
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A synthetic route to tercyclohexanones is described in which alkylation of 4-cyclohexylcyclohexanone with the dianion of 4,4-(ethylenedioxy)cyclohexanecarboxylic acid gives 1-carboxy-1'-hydroxyl-1,1':4',1''-tercyclohexan-4-one ethylene ketal. Decarboxylative dehydration of the latter followed by hydrolysis of the ketal gives 4-(4'-cyclohexylcyclohexylidene)cyclohexanone. Hydrogenation of this compound gives cis- and trans-1,1':4',1''-tecyclohexan-4-one, the latter of which is correlated with authentic trans-1,1':4',1''-tercyclohexane.
- Nidy,Graber,Spinelli,Sih,Johnson
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p. 1053 - 1056
(2007/10/02)
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