Ion-Pair-Directed Borylation of Aromatic Phosphonium Salts.
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Publication Date
2019-10Journal Title
The Journal of organic chemistry
ISSN
0022-3263
Publisher
American Chemical Society
Volume
84
Issue
20
Pages
13124-13134
Language
eng
Type
Article
This Version
VoR
Physical Medium
Print-Electronic
Metadata
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Lee, B., Mihai, M. T., Stojalnikova, V., & Phipps, R. (2019). Ion-Pair-Directed Borylation of Aromatic Phosphonium Salts.. The Journal of organic chemistry, 84 (20), 13124-13134. https://doi.org/10.1021/acs.joc.9b00878
Abstract
Control of positional selectivity in C-H activation reactions remains a challenge for synthetic chemists. Non-covalent
catalysis has the potential to be a powerful strategy to address this challenge. As 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 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 higher meta-selectivity than the corresponding ammonium salts. We propose that the high selectivity occurs
due to an attractive electrostatic interaction between substrate and ligand in the transition state for borylation.
Sponsorship
EPSRC (EP/N005422/1)
Royal Society (uf130004)
European Commission Horizon 2020 (H2020) ERC (757381)
Identifiers
External DOI: https://doi.org/10.1021/acs.joc.9b00878
This record's URL: https://www.repository.cam.ac.uk/handle/1810/293051