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Assessing Alkali‐Metal Effects in the Structures and Reactivity of Mixed‐Ligand Alkyl/Alkoxide Alkali‐Metal Magnesiates

Advancing the understanding of using alkali‐metal alkoxides as additives to organomagnesium reagents in Mg−Br exchange reactions, a homologous series of mixed‐ligand alkyl/alkoxide alkali‐metal magnesiates [MMg(CH(2)SiMe(3))(2)(dmem)](2) [dmem=2‐{[2‐(dimethylamino)ethyl]methylamino} ethoxide; M=Li,...

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Autores principales: Judge, Neil R., Bole, Leonie J., Hevia, Eva
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9306829/
https://www.ncbi.nlm.nih.gov/pubmed/34939701
http://dx.doi.org/10.1002/chem.202104164
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author Judge, Neil R.
Bole, Leonie J.
Hevia, Eva
author_facet Judge, Neil R.
Bole, Leonie J.
Hevia, Eva
author_sort Judge, Neil R.
collection PubMed
description Advancing the understanding of using alkali‐metal alkoxides as additives to organomagnesium reagents in Mg−Br exchange reactions, a homologous series of mixed‐ligand alkyl/alkoxide alkali‐metal magnesiates [MMg(CH(2)SiMe(3))(2)(dmem)](2) [dmem=2‐{[2‐(dimethylamino)ethyl]methylamino} ethoxide; M=Li, 1; Na, 2; (THF)K, 3] has been prepared. Structural and spectroscopic studies have established the constitutions of these heteroleptic/heterometallic species, which are retained in arene solution. Evaluation of their reactivity towards 2‐bromoanisole has uncovered a marked alkali‐metal effect with potassium magnesiate 3 being the most efficient of the three ate reagents. Studies probing the constitution of the exchange product from this reaction suggest that the putative [KMgAr(2)(dmem)](2) (Ar=o‐OMe−C(6)H(4)) intermediate undergoes redistribution into its single metal components [KAr](n) and [MgAr(dmem)](2) (5). This process can be circumvented by using a different potassium alkoxide containing an aliphatic chain such as KOR’ (R’=2‐ethylhexyl) which undergoes co‐complexation with Mg(CH(2)SiMe(3)) to give [KMg(CH(2)SiMe(3))(2)(OR’)](2) (7). This ate, in turn, reacts quantitatively with 2‐bromoanisole furnishing [KMgAr(2)(OR’)](2) (9) which is stable in solution as a bimetallic compound. Collectively this work highlights the complexity of these alkali‐metal mediated Mg−Br exchange reactions, where each reaction component can have a profound effect not only on the success of the reaction; but also the stability of the final metalated intermediates prior to their electrophilic interception.
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spelling pubmed-93068292022-07-28 Assessing Alkali‐Metal Effects in the Structures and Reactivity of Mixed‐Ligand Alkyl/Alkoxide Alkali‐Metal Magnesiates Judge, Neil R. Bole, Leonie J. Hevia, Eva Chemistry Research Articles Advancing the understanding of using alkali‐metal alkoxides as additives to organomagnesium reagents in Mg−Br exchange reactions, a homologous series of mixed‐ligand alkyl/alkoxide alkali‐metal magnesiates [MMg(CH(2)SiMe(3))(2)(dmem)](2) [dmem=2‐{[2‐(dimethylamino)ethyl]methylamino} ethoxide; M=Li, 1; Na, 2; (THF)K, 3] has been prepared. Structural and spectroscopic studies have established the constitutions of these heteroleptic/heterometallic species, which are retained in arene solution. Evaluation of their reactivity towards 2‐bromoanisole has uncovered a marked alkali‐metal effect with potassium magnesiate 3 being the most efficient of the three ate reagents. Studies probing the constitution of the exchange product from this reaction suggest that the putative [KMgAr(2)(dmem)](2) (Ar=o‐OMe−C(6)H(4)) intermediate undergoes redistribution into its single metal components [KAr](n) and [MgAr(dmem)](2) (5). This process can be circumvented by using a different potassium alkoxide containing an aliphatic chain such as KOR’ (R’=2‐ethylhexyl) which undergoes co‐complexation with Mg(CH(2)SiMe(3)) to give [KMg(CH(2)SiMe(3))(2)(OR’)](2) (7). This ate, in turn, reacts quantitatively with 2‐bromoanisole furnishing [KMgAr(2)(OR’)](2) (9) which is stable in solution as a bimetallic compound. Collectively this work highlights the complexity of these alkali‐metal mediated Mg−Br exchange reactions, where each reaction component can have a profound effect not only on the success of the reaction; but also the stability of the final metalated intermediates prior to their electrophilic interception. John Wiley and Sons Inc. 2022-01-27 2022-02-19 /pmc/articles/PMC9306829/ /pubmed/34939701 http://dx.doi.org/10.1002/chem.202104164 Text en © 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH https://creativecommons.org/licenses/by-nc-nd/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc-nd/4.0/ (https://creativecommons.org/licenses/by-nc-nd/4.0/) License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.
spellingShingle Research Articles
Judge, Neil R.
Bole, Leonie J.
Hevia, Eva
Assessing Alkali‐Metal Effects in the Structures and Reactivity of Mixed‐Ligand Alkyl/Alkoxide Alkali‐Metal Magnesiates
title Assessing Alkali‐Metal Effects in the Structures and Reactivity of Mixed‐Ligand Alkyl/Alkoxide Alkali‐Metal Magnesiates
title_full Assessing Alkali‐Metal Effects in the Structures and Reactivity of Mixed‐Ligand Alkyl/Alkoxide Alkali‐Metal Magnesiates
title_fullStr Assessing Alkali‐Metal Effects in the Structures and Reactivity of Mixed‐Ligand Alkyl/Alkoxide Alkali‐Metal Magnesiates
title_full_unstemmed Assessing Alkali‐Metal Effects in the Structures and Reactivity of Mixed‐Ligand Alkyl/Alkoxide Alkali‐Metal Magnesiates
title_short Assessing Alkali‐Metal Effects in the Structures and Reactivity of Mixed‐Ligand Alkyl/Alkoxide Alkali‐Metal Magnesiates
title_sort assessing alkali‐metal effects in the structures and reactivity of mixed‐ligand alkyl/alkoxide alkali‐metal magnesiates
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9306829/
https://www.ncbi.nlm.nih.gov/pubmed/34939701
http://dx.doi.org/10.1002/chem.202104164
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