Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands

Iridium(i) cyclooctadiene complexes featuring O- and N-donor functionalised NHC ligands efficiently catalyse the C-N coupling of amines with alcohols through a borrowing hydrogen mechanism. These catalysts have been applied for the N-alkylation of several aromatic and aliphatic primary amines with a...

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Autores: Jiménez, M.V., Fernández-Tornos, J., González-Lainez, M., Sánchez-Page, B., Modrego, F.J., Oro, L.A., Pérez-Torrente, J.J.
Formato: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2018
País:España
Recursos:Universidad de Zaragoza
Repositorio:Zaguán. Repositorio Digital de la Universidad de Zaragoza
OAI Identifier:oai:zaguan.unizar.es:79138
Acesso em linha:http://zaguan.unizar.es/record/79138
Access Level:acceso abierto
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spelling Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligandsJiménez, M.V.Fernández-Tornos, J.González-Lainez, M.Sánchez-Page, B.Modrego, F.J.Oro, L.A.Pérez-Torrente, J.J.Iridium(i) cyclooctadiene complexes featuring O- and N-donor functionalised NHC ligands efficiently catalyse the C-N coupling of amines with alcohols through a borrowing hydrogen mechanism. These catalysts have been applied for the N-alkylation of several aromatic and aliphatic primary amines with a range of alcohols including benzyl alcohol derivatives, straight-chain primary alcohols and secondary alcohols. The cationic complex [Ir(NCCH3)(cod){MeIm(2-methoxybenzyl)}]+ (cod = 1, 5-cyclooctadiene, MeIm = 3-methylimidazol-2-ylidene) having a rigid O-donor wingtip exhibits the best catalytic performance for the N-alkylation of aniline with benzyl alcohol giving a quantitative conversion to N-benzylaniline in 3 h. Experimental and theoretical studies at the DFT level on the N-alkylation of aniline with benzyl alcohol catalysed by the model compound [IrCl(cod)(IMe)] (IMe = 1, 3-dimethyl-imidazol-2-ylidene) support the participation of the iridium catalyst not only in the alcohol dehydrogenation and imine hydrogenation steps but also in the key step leading to the formation of the new C-N bond. Nucleophilic attack of an iridium-amido species generated in basic medium on the electrophilic aldehyde results in a hemiaminolate intermediate species from which the hemiaminal is released by alcoholysis. The free hemiaminal dehydrates to give the corresponding intermediate imine product that is hydrogenated by the iridium catalyst to the N-alkylated amine product. The iridium(i) complexes featuring functionalised NHC ligands are more active than [IrCl(cod)(IMe)] which highlights the positive influence of the functional group on the N-alkylation catalytic activity.2018info:eu-repo/semantics/articleinfo:eu-repo/semantics/acceptedVersionapplication/pdfhttp://zaguan.unizar.es/record/79138reponame:Zaguán. Repositorio Digital de la Universidad de Zaragozainstname:Universidad de ZaragozaInglésinfo:eu-repo/grantAgreement/ES/DGA-FSE/E07info:eu-repo/grantAgreement/ES/MINECO-FEDER/CTQ2013-42532-Pinfo:eu-repo/grantAgreement/ES/MINECO-FEDER/CTQ2016-75884-Pinfo:eu-repo/semantics/openAccessoai:zaguan.unizar.es:791382026-05-29T13:59:51Z
dc.title.none.fl_str_mv Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands
title Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands
spellingShingle Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands
Jiménez, M.V.
title_short Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands
title_full Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands
title_fullStr Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands
title_full_unstemmed Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands
title_sort Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands
dc.creator.none.fl_str_mv Jiménez, M.V.
Fernández-Tornos, J.
González-Lainez, M.
Sánchez-Page, B.
Modrego, F.J.
Oro, L.A.
Pérez-Torrente, J.J.
author Jiménez, M.V.
author_facet Jiménez, M.V.
Fernández-Tornos, J.
González-Lainez, M.
Sánchez-Page, B.
Modrego, F.J.
Oro, L.A.
Pérez-Torrente, J.J.
author_role author
author2 Fernández-Tornos, J.
González-Lainez, M.
Sánchez-Page, B.
Modrego, F.J.
Oro, L.A.
Pérez-Torrente, J.J.
author2_role author
author
author
author
author
author
description Iridium(i) cyclooctadiene complexes featuring O- and N-donor functionalised NHC ligands efficiently catalyse the C-N coupling of amines with alcohols through a borrowing hydrogen mechanism. These catalysts have been applied for the N-alkylation of several aromatic and aliphatic primary amines with a range of alcohols including benzyl alcohol derivatives, straight-chain primary alcohols and secondary alcohols. The cationic complex [Ir(NCCH3)(cod){MeIm(2-methoxybenzyl)}]+ (cod = 1, 5-cyclooctadiene, MeIm = 3-methylimidazol-2-ylidene) having a rigid O-donor wingtip exhibits the best catalytic performance for the N-alkylation of aniline with benzyl alcohol giving a quantitative conversion to N-benzylaniline in 3 h. Experimental and theoretical studies at the DFT level on the N-alkylation of aniline with benzyl alcohol catalysed by the model compound [IrCl(cod)(IMe)] (IMe = 1, 3-dimethyl-imidazol-2-ylidene) support the participation of the iridium catalyst not only in the alcohol dehydrogenation and imine hydrogenation steps but also in the key step leading to the formation of the new C-N bond. Nucleophilic attack of an iridium-amido species generated in basic medium on the electrophilic aldehyde results in a hemiaminolate intermediate species from which the hemiaminal is released by alcoholysis. The free hemiaminal dehydrates to give the corresponding intermediate imine product that is hydrogenated by the iridium catalyst to the N-alkylated amine product. The iridium(i) complexes featuring functionalised NHC ligands are more active than [IrCl(cod)(IMe)] which highlights the positive influence of the functional group on the N-alkylation catalytic activity.
publishDate 2018
dc.date.none.fl_str_mv 2018
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
format article
status_str acceptedVersion
dc.identifier.none.fl_str_mv http://zaguan.unizar.es/record/79138
url http://zaguan.unizar.es/record/79138
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv info:eu-repo/grantAgreement/ES/DGA-FSE/E07
info:eu-repo/grantAgreement/ES/MINECO-FEDER/CTQ2013-42532-P
info:eu-repo/grantAgreement/ES/MINECO-FEDER/CTQ2016-75884-P
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv
publisher.none.fl_str_mv
dc.source.none.fl_str_mv reponame:Zaguán. Repositorio Digital de la Universidad de Zaragoza
instname:Universidad de Zaragoza
instname_str Universidad de Zaragoza
reponame_str Zaguán. Repositorio Digital de la Universidad de Zaragoza
collection Zaguán. Repositorio Digital de la Universidad de Zaragoza
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