Please use this identifier to cite or link to this item: http://repositorio.ufla.br/jspui/handle/1/32813
metadata.artigo.dc.title: Theoretical study on the anomeric effect in α-substituted tetrahydropyrans and piperidines
metadata.artigo.dc.creator: Martins, Francisco A.
Silla, Josué M.
Freitas, Matheus P.
metadata.artigo.dc.subject: Anomeric effect
Hyperconjugation
Steric effect
Coupling constant
Heterocycles
Efeito anomérico
Hiperconjugação
Efeito estérico
Constante de acoplamento
Heterociclos
metadata.artigo.dc.publisher: Elsevier
metadata.artigo.dc.date.issued: 8-Nov-2017
metadata.artigo.dc.identifier.citation: MARTINS, F. A.; SILLA, J. M.; FREITAS, M. P. Theoretical study on the anomeric effect in α-substituted tetrahydropyrans and piperidines. Carbohydrate Research, Amsterdam, v. 451, p. 29-35, 8 Nov. 2017.
metadata.artigo.dc.description.abstract: Conformational effects, including some controversial examples, have been reported in this work for 2-substituted tetrahydropyrans and piperidines, and for the respective protonated compounds [substituent = F, OH, OCH3, NH2, NHCH3 and N(CH3)2]. Hyperconjugation plays a major role in most cases, either due to endo or exo-anomeric interactions, especially when nitrogen is the electron donor to an antiperiplanar σ* orbital. This interaction also seems to contribute for the Perlin and reverse fluorine Perlin-like effects, which are related to the relative magnitude of 1JC,H and 1JC,F coupling constants, respectively, in axial and equatorial conformers. However, the preference for an equatorial conformation appears when a hydrogen or methyl group of the substituent faces the ring, increasing the steric repulsion, even if concomitant with a hyperconjugative interaction in the axial isomer, such as for the well-known 2-aminotetrahydropyran. Unlike some reports in the literature, the gas phase 2-hydroxypiperidine experiences the herein called reverse anomeric effect, although the highly stabilizing nN → σ*C-O interaction in the axial isomer. Overall, steric effects should be taken into account when deciding for the normal or reverse anomeric effects as determinant factors of the stereochemical control of carbohydrate-like molecules.
metadata.artigo.dc.identifier.uri: https://www.sciencedirect.com/science/article/pii/S0008621517305906?via%3Dihub
http://repositorio.ufla.br/jspui/handle/1/32813
metadata.artigo.dc.language: en_US
Appears in Collections:DQI - Artigos publicados em periódicos

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