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Ion-Pair-Directed Borylation of Aromatic Phosphonium Salts

[Image: see text] Control of positional selectivity in C–H activation reactions remains a challenge for synthetic chemists. Noncovalent catalysis has the potential to be a powerful strategy to address this challenge. As a part of our ongoing investigations into the use of ion-pairing interactions in...

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Autores principales: Lee, Bernadette, Mihai, Madalina T., Stojalnikova, Violeta, Phipps, Robert J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2019
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6804313/
https://www.ncbi.nlm.nih.gov/pubmed/31117572
http://dx.doi.org/10.1021/acs.joc.9b00878
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author Lee, Bernadette
Mihai, Madalina T.
Stojalnikova, Violeta
Phipps, Robert J.
author_facet Lee, Bernadette
Mihai, Madalina T.
Stojalnikova, Violeta
Phipps, Robert J.
author_sort Lee, Bernadette
collection PubMed
description [Image: see text] Control of positional selectivity in C–H activation reactions remains a challenge for synthetic chemists. Noncovalent catalysis has the potential to be a powerful strategy to address this challenge. As a part of our ongoing investigations into the use of ion-pairing interactions in site-selective catalysis, we demonstrate that several classes of aromatic phosphonium salts undergo iridium-catalyzed C–H borylation with a high selectivity for the arene meta position. This is achieved using a bifunctional bipyridine ligand bearing a pendant sulfonate group, which had previously been successful for borylation of aromatic ammonium salts. In this case, the phosphonium salts give a higher meta selectivity than the corresponding ammonium salts. We propose that the high selectivity occurs due to an attractive electrostatic interaction between the substrate and the ligand in the transition state for borylation.
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spelling pubmed-68043132019-10-23 Ion-Pair-Directed Borylation of Aromatic Phosphonium Salts Lee, Bernadette Mihai, Madalina T. Stojalnikova, Violeta Phipps, Robert J. J Org Chem [Image: see text] Control of positional selectivity in C–H activation reactions remains a challenge for synthetic chemists. Noncovalent catalysis has the potential to be a powerful strategy to address this challenge. As a part of our ongoing investigations into the use of ion-pairing interactions in site-selective catalysis, we demonstrate that several classes of aromatic phosphonium salts undergo iridium-catalyzed C–H borylation with a high selectivity for the arene meta position. This is achieved using a bifunctional bipyridine ligand bearing a pendant sulfonate group, which had previously been successful for borylation of aromatic ammonium salts. In this case, the phosphonium salts give a higher meta selectivity than the corresponding ammonium salts. We propose that the high selectivity occurs due to an attractive electrostatic interaction between the substrate and the ligand in the transition state for borylation. American Chemical Society 2019-05-22 2019-10-18 /pmc/articles/PMC6804313/ /pubmed/31117572 http://dx.doi.org/10.1021/acs.joc.9b00878 Text en Copyright © 2019 American Chemical Society This is an open access article published under a Creative Commons Attribution (CC-BY) License (http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) , which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
spellingShingle Lee, Bernadette
Mihai, Madalina T.
Stojalnikova, Violeta
Phipps, Robert J.
Ion-Pair-Directed Borylation of Aromatic Phosphonium Salts
title Ion-Pair-Directed Borylation of Aromatic Phosphonium Salts
title_full Ion-Pair-Directed Borylation of Aromatic Phosphonium Salts
title_fullStr Ion-Pair-Directed Borylation of Aromatic Phosphonium Salts
title_full_unstemmed Ion-Pair-Directed Borylation of Aromatic Phosphonium Salts
title_short Ion-Pair-Directed Borylation of Aromatic Phosphonium Salts
title_sort ion-pair-directed borylation of aromatic phosphonium salts
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6804313/
https://www.ncbi.nlm.nih.gov/pubmed/31117572
http://dx.doi.org/10.1021/acs.joc.9b00878
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