The effect of carbonyl group in the asymmetry of3,4J CH coupling constants in norbornanones

A rationalization of the known difference between the 3,4J C4H1 and 3,4JC1H4 couplings transmitted mainly through the 7-bridge in norbomanone is presented in terms of the effects of hyperconjugative interactions involving the carbonyl group. Theoretical and experimental studies of 3,4JCH couplings w...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Dos Santos, F.P., Tormena, C.F., Contreras, R.H., Rittner, R., Magalhães, A.
Formato:	JOUR
Materias:	3,4JCH Carbonyl group NMR Norbornanones
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_07491581_v46_n2_p107_DosSantos
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	todo:paper_07491581_v46_n2_p107_DosSantos
record_format	dspace
spelling	todo:paper_07491581_v46_n2_p107_DosSantos2023-10-03T15:39:30Z The effect of carbonyl group in the asymmetry of3,4J CH coupling constants in norbornanones Dos Santos, F.P. Tormena, C.F. Contreras, R.H. Rittner, R. Magalhães, A. 3,4JCH Carbonyl group NMR Norbornanones A rationalization of the known difference between the 3,4J C4H1 and 3,4JC1H4 couplings transmitted mainly through the 7-bridge in norbomanone is presented in terms of the effects of hyperconjugative interactions involving the carbonyl group. Theoretical and experimental studies of 3,4JCH couplings were carried out in 3-endo- and 3-exo-X-2-norbornanone derivatives (X = Cl, Br) and in exo- and endo-2-noborneol compounds. Hyperconjugative interactions were studied with the natural bond orbital (NBO) method. Hyperconjugative interactions involving the carbonyl πC2 = O and σC2=O antibonding orbitais produce a decrease of three-bond contribution to both 3,4JC4H1 and 3,4JC1H4 couplings. However, the latter antibonding orbital also undergoes a strong σC3-C4 → σC2=O interaction, which defines an additional coupling pathway for 3,4JC4H1 but not for 3,4JC1H4. This pathway is similar to that known for homoallylic couplings, the only difference being the nature of the intermediate antibonding orbital; i.e. for 3,4JC4H1 it is of σ-type, while in homoallylic couplings it is of π-type. Copyright © 2007 John Wiley & Sons, Ltd. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_07491581_v46_n2_p107_DosSantos
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	3,4JCH Carbonyl group NMR Norbornanones
spellingShingle	3,4JCH Carbonyl group NMR Norbornanones Dos Santos, F.P. Tormena, C.F. Contreras, R.H. Rittner, R. Magalhães, A. The effect of carbonyl group in the asymmetry of3,4J CH coupling constants in norbornanones
topic_facet	3,4JCH Carbonyl group NMR Norbornanones
description	A rationalization of the known difference between the 3,4J C4H1 and 3,4JC1H4 couplings transmitted mainly through the 7-bridge in norbomanone is presented in terms of the effects of hyperconjugative interactions involving the carbonyl group. Theoretical and experimental studies of 3,4JCH couplings were carried out in 3-endo- and 3-exo-X-2-norbornanone derivatives (X = Cl, Br) and in exo- and endo-2-noborneol compounds. Hyperconjugative interactions were studied with the natural bond orbital (NBO) method. Hyperconjugative interactions involving the carbonyl πC2 = O and σC2=O antibonding orbitais produce a decrease of three-bond contribution to both 3,4JC4H1 and 3,4JC1H4 couplings. However, the latter antibonding orbital also undergoes a strong σC3-C4 → σC2=O interaction, which defines an additional coupling pathway for 3,4JC4H1 but not for 3,4JC1H4. This pathway is similar to that known for homoallylic couplings, the only difference being the nature of the intermediate antibonding orbital; i.e. for 3,4JC4H1 it is of σ-type, while in homoallylic couplings it is of π-type. Copyright © 2007 John Wiley & Sons, Ltd.
format	JOUR
author	Dos Santos, F.P. Tormena, C.F. Contreras, R.H. Rittner, R. Magalhães, A.
author_facet	Dos Santos, F.P. Tormena, C.F. Contreras, R.H. Rittner, R. Magalhães, A.
author_sort	Dos Santos, F.P.
title	The effect of carbonyl group in the asymmetry of3,4J CH coupling constants in norbornanones
title_short	The effect of carbonyl group in the asymmetry of3,4J CH coupling constants in norbornanones
title_full	The effect of carbonyl group in the asymmetry of3,4J CH coupling constants in norbornanones
title_fullStr	The effect of carbonyl group in the asymmetry of3,4J CH coupling constants in norbornanones
title_full_unstemmed	The effect of carbonyl group in the asymmetry of3,4J CH coupling constants in norbornanones
title_sort	effect of carbonyl group in the asymmetry of3,4j ch coupling constants in norbornanones
url	http://hdl.handle.net/20.500.12110/paper_07491581_v46_n2_p107_DosSantos
work_keys_str_mv	AT dossantosfp theeffectofcarbonylgroupintheasymmetryof34jchcouplingconstantsinnorbornanones AT tormenacf theeffectofcarbonylgroupintheasymmetryof34jchcouplingconstantsinnorbornanones AT contrerasrh theeffectofcarbonylgroupintheasymmetryof34jchcouplingconstantsinnorbornanones AT rittnerr theeffectofcarbonylgroupintheasymmetryof34jchcouplingconstantsinnorbornanones AT magalhaesa theeffectofcarbonylgroupintheasymmetryof34jchcouplingconstantsinnorbornanones AT dossantosfp effectofcarbonylgroupintheasymmetryof34jchcouplingconstantsinnorbornanones AT tormenacf effectofcarbonylgroupintheasymmetryof34jchcouplingconstantsinnorbornanones AT contrerasrh effectofcarbonylgroupintheasymmetryof34jchcouplingconstantsinnorbornanones AT rittnerr effectofcarbonylgroupintheasymmetryof34jchcouplingconstantsinnorbornanones AT magalhaesa effectofcarbonylgroupintheasymmetryof34jchcouplingconstantsinnorbornanones
_version_	1782029444684185600

The effect of carbonyl group in the asymmetry of3,4J CH coupling constants in norbornanones

Ejemplares similares