1H NMR Spectra. Part 28: Proton chemical shifts and couplings in three-membered rings. A ring current model for cyclopropane and a novel dihedral angle dependence for 3JHH couplings involving the epoxy proton

dc.creatorAbraham, RJ
dc.creatorLeonard, P
dc.creatorTormena, CF
dc.date2012
dc.dateAPR
dc.date2014-07-30T13:38:43Z
dc.date2015-11-26T16:28:54Z
dc.date2014-07-30T13:38:43Z
dc.date2015-11-26T16:28:54Z
dc.date.accessioned2018-03-28T23:09:58Z
dc.date.available2018-03-28T23:09:58Z
dc.identifierMagnetic Resonance In Chemistry. Wiley-blackwell, v. 50, n. 4, n. 305, n. 313, 2012.
dc.identifier0749-1581
dc.identifierWOS:000302149800009
dc.identifier10.1002/mrc.3808
dc.identifierhttp://www.repositorio.unicamp.br/jspui/handle/REPOSIP/52529
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/52529
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1269592
dc.descriptionFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.descriptionConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.descriptionThe 1H chemical shifts of selected three-membered ring compounds in CDCl3 solvent were obtained. This allowed the determination of the substituent chemical shifts of the substituents in the three-membered rings and the long-range effect of these rings on the distant protons. The substituent chemical shifts of common substituents in the cyclopropane ring differ considerably from the same substituents in acyclic fragments and in cyclohexane and were modelled in terms of a three-bond (gamma)-effect. For long-range protons (more than three bonds removed), the substituent effects of the cyclopropane ring were analysed in terms of the cyclopropane magnetic anisotropy and steric effect. The cyclopropane magnetic anisotropy (ring current) shift was modelled by (a) a single equivalent dipole perpendicular to and at the centre of the cyclopropane ring and (b) by three identical equivalent dipoles perpendicular to the ring placed at each carbon atom. Model (b) gave a more accurate description of the 1H chemical shifts and was the selected model. After parameterization, the overall root mean square error for the dataset of 289 entries was 0.068 ppm. The anisotropic effects are significant for the cyclopropane protons (ca 1 ppm) but decrease rapidly with distance. The heterocyclic rings of oxirane, thiirane and aziridine do not possess a ring current. 3JHH couplings of the epoxy ring proton with side-chain protons were obtained and shown to be dependent on both the H-C-C-H and H-C-C-O orientations. Both density functional theory calculations and a simple Karplus-type equation gave general agreement with the observed couplings (root mean square error 0.5 Hz over a 10-Hz range). Copyright (c) 2012 John Wiley & Sons, Ltd.
dc.description50
dc.description4
dc.description305
dc.description313
dc.descriptionAstraZeneca
dc.descriptionEPSRC
dc.descriptionFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.descriptionConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.descriptionFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.descriptionConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.descriptionFAPESP [10/10993-9]
dc.languageen
dc.publisherWiley-blackwell
dc.publisherMalden
dc.publisherEUA
dc.relationMagnetic Resonance In Chemistry
dc.relationMagn. Reson. Chem.
dc.rightsfechado
dc.rightshttp://olabout.wiley.com/WileyCDA/Section/id-406071.html
dc.sourceWeb of Science
dc.subject1H chemical shifts
dc.subjectcyclopropanes
dc.subjectoxiranes
dc.subjectthiiaranes
dc.subjectaziridines
dc.subjectcyclopropane ring current
dc.subject3JHH couplings of epoxy protons
dc.subjectDensity-functional Theory
dc.subjectMagnetic-resonance
dc.subjectCyclic-compounds
dc.subjectC-13 Nmr
dc.subjectDerivatives
dc.subjectH-1
dc.subjectConformations
dc.subjectEpoxides
dc.subjectStereochemistry
dc.subjectSpectroscopy
dc.title1H NMR Spectra. Part 28: Proton chemical shifts and couplings in three-membered rings. A ring current model for cyclopropane and a novel dihedral angle dependence for 3JHH couplings involving the epoxy proton
dc.typeArtículos de revistas


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