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1.
Molecular mechanics, ab initio (RHF) and density functional (DFT/B3LYP) methods are applied to investigate the conformational preferences of the methoxycarbonyl group of the (±)methyl 3-hydroxy-1-azabicyclo[2.2.2]octane-3-carboxylate. 1H and 13C chemical shifts are also calculated by the GIAO/DFT approach and compared with experimental values. Both theoretical and experimental data account for almost eclipsed conformations with different degrees of distortion from the ideal geometry. It is found that calculations at the B3LYP/6-311G(d,p) level are relatively more reliable to explain the behaviour of the alkoxycarbonyl moiety of 2-hydroxyesters derived from the (±)3-hydroxy-1-azabicyclo[2.2.2]octane-3-carboxylic acid. 相似文献
2.
S. G. Klepikova V. K. Yu E. E. Fomicheva R. D. Mukhasheva K. D. Praliev K. D. Berlin 《Chemistry of Heterocyclic Compounds》2008,44(11):1398-1403
1H NMR spectroscopy was used to establish that 7-alkoxyalkyl-3-thia-7-azabicyclo[3.3.1]nonan-9-ones and their decarbonylated
derivatives in deuterochloroform solution exist in the double chair conformation. The predominantly formed secondary alcohols
isomers have preferred double chair conformation with the hydroxyl group equatorial relative to the plane of the piperidine
ring. On the other hand, the epimeric alcohols have predominant boat-chair conformation; the piperidine ring takes the boat
form due to intramolecular hydrogen bonding between the unshared electron pair of the nitrogen atom and hydroxyl group proton.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1716–1725, November, 2008. 相似文献