On the unusual 2JC2-Hf coupling dependence on syn/anti CHO conformation in 5-X-furan-2-carboxaldehydes

A remarkable difference for 2JC2-H f, coupling constant in syn and anti conformers of 5-X-furan-2-carboxaldehydes (X = CH3, Ph, NO2, Br) and a rationalization of this difference are reported. On the basis of the current knowledge of the Fermi-contact term transmission, a rather unusual dual-coupling...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autor principal:	Contreras, Rubén Horacio
Publicado:	2008
Materias:	Fermi-contact transmission Furfural Geminal NMR couplings NBO Through space aldehyde furan derivative article chemical model chemistry conformation electron methodology nuclear magnetic resonance spectroscopy quantum theory standard stereoisomerism Aldehydes Electrons Furans Magnetic Resonance Spectroscopy Models, Chemical Molecular Conformation Quantum Theory Reference Standards Stereoisomerism
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07491581_v46_n9_p846_Perez http://hdl.handle.net/20.500.12110/paper_07491581_v46_n9_p846_Perez
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_07491581_v46_n9_p846_Perez
record_format	dspace
spelling	paper:paper_07491581_v46_n9_p846_Perez2023-06-08T15:45:37Z On the unusual 2JC2-Hf coupling dependence on syn/anti CHO conformation in 5-X-furan-2-carboxaldehydes Contreras, Rubén Horacio Fermi-contact transmission Furfural Geminal NMR couplings NBO Through space aldehyde furan derivative article chemical model chemistry conformation electron methodology nuclear magnetic resonance spectroscopy quantum theory standard stereoisomerism Aldehydes Electrons Furans Magnetic Resonance Spectroscopy Models, Chemical Molecular Conformation Quantum Theory Reference Standards Stereoisomerism A remarkable difference for 2JC2-H f, coupling constant in syn and anti conformers of 5-X-furan-2-carboxaldehydes (X = CH3, Ph, NO2, Br) and a rationalization of this difference are reported. On the basis of the current knowledge of the Fermi-contact term transmission, a rather unusual dual-coupling pathway in the syn conformer is presented. The additional coupling pathway resembles somewhat that of the JH-H in homoallylic couplings, which are transmitted by hyperconjugative interactions involving the πC=C electronic system. The homoallylic coupling pathway can be labeled as σC-H ←-πc=c → σC-H. In the present case, this additional coupling pathway, using an analogous notation, can be labeled as σ* c2-cc ← LP1(O 1)⋯ LP2(Oc) → σ* Cc-Hf (σ*C2 -C c) where O1 and Oc stand for the ring and carbonyl O atoms, respectively. This additional coupling pathway is not activated in the anti conformers since both oxygen lone pairs do not overlap. Copyright © 2008 John Wiley & Sons, Ltd. Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2008 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07491581_v46_n9_p846_Perez http://hdl.handle.net/20.500.12110/paper_07491581_v46_n9_p846_Perez
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Fermi-contact transmission Furfural Geminal NMR couplings NBO Through space aldehyde furan derivative article chemical model chemistry conformation electron methodology nuclear magnetic resonance spectroscopy quantum theory standard stereoisomerism Aldehydes Electrons Furans Magnetic Resonance Spectroscopy Models, Chemical Molecular Conformation Quantum Theory Reference Standards Stereoisomerism
spellingShingle	Fermi-contact transmission Furfural Geminal NMR couplings NBO Through space aldehyde furan derivative article chemical model chemistry conformation electron methodology nuclear magnetic resonance spectroscopy quantum theory standard stereoisomerism Aldehydes Electrons Furans Magnetic Resonance Spectroscopy Models, Chemical Molecular Conformation Quantum Theory Reference Standards Stereoisomerism Contreras, Rubén Horacio On the unusual 2JC2-Hf coupling dependence on syn/anti CHO conformation in 5-X-furan-2-carboxaldehydes
topic_facet	Fermi-contact transmission Furfural Geminal NMR couplings NBO Through space aldehyde furan derivative article chemical model chemistry conformation electron methodology nuclear magnetic resonance spectroscopy quantum theory standard stereoisomerism Aldehydes Electrons Furans Magnetic Resonance Spectroscopy Models, Chemical Molecular Conformation Quantum Theory Reference Standards Stereoisomerism
description	A remarkable difference for 2JC2-H f, coupling constant in syn and anti conformers of 5-X-furan-2-carboxaldehydes (X = CH3, Ph, NO2, Br) and a rationalization of this difference are reported. On the basis of the current knowledge of the Fermi-contact term transmission, a rather unusual dual-coupling pathway in the syn conformer is presented. The additional coupling pathway resembles somewhat that of the JH-H in homoallylic couplings, which are transmitted by hyperconjugative interactions involving the πC=C electronic system. The homoallylic coupling pathway can be labeled as σC-H ←-πc=c → σC-H. In the present case, this additional coupling pathway, using an analogous notation, can be labeled as σ* c2-cc ← LP1(O 1)⋯ LP2(Oc) → σ* Cc-Hf (σ*C2 -C c) where O1 and Oc stand for the ring and carbonyl O atoms, respectively. This additional coupling pathway is not activated in the anti conformers since both oxygen lone pairs do not overlap. Copyright © 2008 John Wiley & Sons, Ltd.
author	Contreras, Rubén Horacio
author_facet	Contreras, Rubén Horacio
author_sort	Contreras, Rubén Horacio
title	On the unusual 2JC2-Hf coupling dependence on syn/anti CHO conformation in 5-X-furan-2-carboxaldehydes
title_short	On the unusual 2JC2-Hf coupling dependence on syn/anti CHO conformation in 5-X-furan-2-carboxaldehydes
title_full	On the unusual 2JC2-Hf coupling dependence on syn/anti CHO conformation in 5-X-furan-2-carboxaldehydes
title_fullStr	On the unusual 2JC2-Hf coupling dependence on syn/anti CHO conformation in 5-X-furan-2-carboxaldehydes
title_full_unstemmed	On the unusual 2JC2-Hf coupling dependence on syn/anti CHO conformation in 5-X-furan-2-carboxaldehydes
title_sort	on the unusual 2jc2-hf coupling dependence on syn/anti cho conformation in 5-x-furan-2-carboxaldehydes
publishDate	2008
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07491581_v46_n9_p846_Perez http://hdl.handle.net/20.500.12110/paper_07491581_v46_n9_p846_Perez
work_keys_str_mv	AT contrerasrubenhoracio ontheunusual2jc2hfcouplingdependenceonsynantichoconformationin5xfuran2carboxaldehydes
_version_	1768543615672385536

On the unusual 2JC2-Hf coupling dependence on syn/anti CHO conformation in 5-X-furan-2-carboxaldehydes

Ejemplares similares