Methoxy group conformation effects on 13C NMR parameters in 1‐cis‐methoxy‐ and 1‐trans‐methoxy‐1,3‐trans‐butadiene

The proton‐coupled 13C NMR spectra of 1‐trans‐methoxy‐ (2) and 1‐cis‐methoxy‐1,3‐trans‐butadiene (3) are consistent with a methoxy heavy atom planar conformation with s‐syn and s‐anti orientations, respectively. Ab initio 6–31G* calculations confirmed such conformations. They were taken as model com...

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Detalles Bibliográficos
Autores principales: Biekofsky, Rodolfo Roberto, Contreras, Rubén Horacio
Publicado: 1994
Materias:
13C NMR
1‐cis‐Methoxy‐1,3‐trans‐butadiene
1‐trans‐Methoxy‐1,3‐trans‐butadiene
Ab initio calculations
Conformation
NMR
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07491581_v32_n4_p199_Esteban
http://hdl.handle.net/20.500.12110/paper_07491581_v32_n4_p199_Esteban
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_07491581_v32_n4_p199_Esteban
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spelling paper:paper_07491581_v32_n4_p199_Esteban2023-06-08T15:45:30Z Methoxy group conformation effects on 13C NMR parameters in 1‐cis‐methoxy‐ and 1‐trans‐methoxy‐1,3‐trans‐butadiene Biekofsky, Rodolfo Roberto Contreras, Rubén Horacio 13C NMR 1‐cis‐Methoxy‐1,3‐trans‐butadiene 1‐trans‐Methoxy‐1,3‐trans‐butadiene Ab initio calculations Conformation NMR The proton‐coupled 13C NMR spectra of 1‐trans‐methoxy‐ (2) and 1‐cis‐methoxy‐1,3‐trans‐butadiene (3) are consistent with a methoxy heavy atom planar conformation with s‐syn and s‐anti orientations, respectively. Ab initio 6–31G* calculations confirmed such conformations. They were taken as model compounds to determine the influence of electrostatic interactions on the methoxy 13C NMR parameters. A shielding increase of 4 ppm is observed in 2, with respect to 3, for the OMe 13C chemical shift in an s‐syn conformation and is ascribed to the attraction between the methyl and vinyl moieties as proposed by Li and Chesnut. The methyl 1J(C,H) coupling is not affected by this interaction, showing that the carbon 2p electrons are more polarizable than those in the 2s orbital. Copyright © 1994 John Wiley & Sons Limited Fil:Biekofsky, R.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1994 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07491581_v32_n4_p199_Esteban http://hdl.handle.net/20.500.12110/paper_07491581_v32_n4_p199_Esteban
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic 13C NMR
1‐cis‐Methoxy‐1,3‐trans‐butadiene
1‐trans‐Methoxy‐1,3‐trans‐butadiene
Ab initio calculations
Conformation
NMR
spellingShingle 13C NMR
1‐cis‐Methoxy‐1,3‐trans‐butadiene
1‐trans‐Methoxy‐1,3‐trans‐butadiene
Ab initio calculations
Conformation
NMR
Biekofsky, Rodolfo Roberto
Contreras, Rubén Horacio
Methoxy group conformation effects on 13C NMR parameters in 1‐cis‐methoxy‐ and 1‐trans‐methoxy‐1,3‐trans‐butadiene
topic_facet 13C NMR
1‐cis‐Methoxy‐1,3‐trans‐butadiene
1‐trans‐Methoxy‐1,3‐trans‐butadiene
Ab initio calculations
Conformation
NMR
description The proton‐coupled 13C NMR spectra of 1‐trans‐methoxy‐ (2) and 1‐cis‐methoxy‐1,3‐trans‐butadiene (3) are consistent with a methoxy heavy atom planar conformation with s‐syn and s‐anti orientations, respectively. Ab initio 6–31G* calculations confirmed such conformations. They were taken as model compounds to determine the influence of electrostatic interactions on the methoxy 13C NMR parameters. A shielding increase of 4 ppm is observed in 2, with respect to 3, for the OMe 13C chemical shift in an s‐syn conformation and is ascribed to the attraction between the methyl and vinyl moieties as proposed by Li and Chesnut. The methyl 1J(C,H) coupling is not affected by this interaction, showing that the carbon 2p electrons are more polarizable than those in the 2s orbital. Copyright © 1994 John Wiley & Sons Limited
author Biekofsky, Rodolfo Roberto
Contreras, Rubén Horacio
author_facet Biekofsky, Rodolfo Roberto
Contreras, Rubén Horacio
author_sort Biekofsky, Rodolfo Roberto
title Methoxy group conformation effects on 13C NMR parameters in 1‐cis‐methoxy‐ and 1‐trans‐methoxy‐1,3‐trans‐butadiene
title_short Methoxy group conformation effects on 13C NMR parameters in 1‐cis‐methoxy‐ and 1‐trans‐methoxy‐1,3‐trans‐butadiene
title_full Methoxy group conformation effects on 13C NMR parameters in 1‐cis‐methoxy‐ and 1‐trans‐methoxy‐1,3‐trans‐butadiene
title_fullStr Methoxy group conformation effects on 13C NMR parameters in 1‐cis‐methoxy‐ and 1‐trans‐methoxy‐1,3‐trans‐butadiene
title_full_unstemmed Methoxy group conformation effects on 13C NMR parameters in 1‐cis‐methoxy‐ and 1‐trans‐methoxy‐1,3‐trans‐butadiene
title_sort methoxy group conformation effects on 13c nmr parameters in 1‐cis‐methoxy‐ and 1‐trans‐methoxy‐1,3‐trans‐butadiene
publishDate 1994
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07491581_v32_n4_p199_Esteban
http://hdl.handle.net/20.500.12110/paper_07491581_v32_n4_p199_Esteban
work_keys_str_mv AT biekofskyrodolforoberto methoxygroupconformationeffectson13cnmrparametersin1cismethoxyand1transmethoxy13transbutadiene
AT contrerasrubenhoracio methoxygroupconformationeffectson13cnmrparametersin1cismethoxyand1transmethoxy13transbutadiene
_version_ 1768544044669992960

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