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(183)W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis

Triarylsilanolates are privileged ancillary ligands for molybdenum alkylidyne catalysts for alkyne metathesis but lead to disappointing results and poor stability in the tungsten series. (1)H,(183)W heteronuclear multiple bond correlation spectroscopy, exploiting a favorable (5) J‐coupling between t...

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Autores principales: Hillenbrand, Julius, Leutzsch, Markus, Gordon, Christopher P., Copéret, Christophe, Fürstner, Alois
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756321/
https://www.ncbi.nlm.nih.gov/pubmed/32820864
http://dx.doi.org/10.1002/anie.202009975
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author Hillenbrand, Julius
Leutzsch, Markus
Gordon, Christopher P.
Copéret, Christophe
Fürstner, Alois
author_facet Hillenbrand, Julius
Leutzsch, Markus
Gordon, Christopher P.
Copéret, Christophe
Fürstner, Alois
author_sort Hillenbrand, Julius
collection PubMed
description Triarylsilanolates are privileged ancillary ligands for molybdenum alkylidyne catalysts for alkyne metathesis but lead to disappointing results and poor stability in the tungsten series. (1)H,(183)W heteronuclear multiple bond correlation spectroscopy, exploiting a favorable (5) J‐coupling between the (183)W center and the peripheral protons on the alkylidyne cap, revealed that these ligands upregulate the Lewis acidity to an extent that the tungstenacyclobutadiene formed in the initial [2+2] cycloaddition step is over‐stabilized and the catalytic turnover brought to a halt. Guided by the (183)W NMR shifts as a proxy for the Lewis acidity of the central atom and by an accompanying chemical shift tensor analysis of the alkylidyne unit, the ligand design was revisited and a more strongly π‐donating all‐alkoxide ligand prepared. The new expanded chelate complex has a tempered Lewis acidity and outperforms the classical Schrock catalyst, carrying monodentate tert‐butoxy ligands, in terms of rate and functional‐group compatibility.
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spelling pubmed-77563212020-12-28 (183)W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis Hillenbrand, Julius Leutzsch, Markus Gordon, Christopher P. Copéret, Christophe Fürstner, Alois Angew Chem Int Ed Engl Research Articles Triarylsilanolates are privileged ancillary ligands for molybdenum alkylidyne catalysts for alkyne metathesis but lead to disappointing results and poor stability in the tungsten series. (1)H,(183)W heteronuclear multiple bond correlation spectroscopy, exploiting a favorable (5) J‐coupling between the (183)W center and the peripheral protons on the alkylidyne cap, revealed that these ligands upregulate the Lewis acidity to an extent that the tungstenacyclobutadiene formed in the initial [2+2] cycloaddition step is over‐stabilized and the catalytic turnover brought to a halt. Guided by the (183)W NMR shifts as a proxy for the Lewis acidity of the central atom and by an accompanying chemical shift tensor analysis of the alkylidyne unit, the ligand design was revisited and a more strongly π‐donating all‐alkoxide ligand prepared. The new expanded chelate complex has a tempered Lewis acidity and outperforms the classical Schrock catalyst, carrying monodentate tert‐butoxy ligands, in terms of rate and functional‐group compatibility. John Wiley and Sons Inc. 2020-09-24 2020-11-23 /pmc/articles/PMC7756321/ /pubmed/32820864 http://dx.doi.org/10.1002/anie.202009975 Text en © 2020 The Authors. Published by Wiley-VCH GmbH This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Articles
Hillenbrand, Julius
Leutzsch, Markus
Gordon, Christopher P.
Copéret, Christophe
Fürstner, Alois
(183)W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis
title (183)W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis
title_full (183)W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis
title_fullStr (183)W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis
title_full_unstemmed (183)W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis
title_short (183)W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis
title_sort (183)w nmr spectroscopy guides the search for tungsten alkylidyne catalysts for alkyne metathesis
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756321/
https://www.ncbi.nlm.nih.gov/pubmed/32820864
http://dx.doi.org/10.1002/anie.202009975
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