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Reactivity of Lewis acid activated diaza- and dithiaboroles in electrophilic arene borylation

Solomon, Sophia A., Del Grosso, Alessandro, Clark, Ewan R., Bagutski, Viktor, McDouall, Joseph J.W., Ingleson, Michael J. (2012) Reactivity of Lewis acid activated diaza- and dithiaboroles in electrophilic arene borylation. Organometallics, 31 (5). pp. 1908-1916. ISSN 0276-7333. (doi:10.1021/om201228e) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Official URL
http://www.dx.doi.org/10.1021/om201228e

Abstract

Hydride abstraction from N,N�-bis(adamantyl)-1-hydrido-1,3,2- benzodiazaborole with catalytic [Ph 3C][closo-CB 11H 6Br 6] resulted in a low yield of arene borylation and a major product derived from migration of both adamantyl groups to the arene backbone. In contrast, the related aryl-substituted diazaborole N,N�-(2,6-diisopropylphenyl)-1-bromo-1,3,2-diazaborole did not borylate benzene or toluene, being resistant to halide abstraction even with strong halide acceptors: e.g., [Et 3Si][closo-CB 11H 6Br 6]. The reactivity disparity arises from greater steric shielding of the boron p z orbital in the 2,6-diisopropylphenyl- substituted diazaboroles. Boron electrophiles derived from 1-chloro-1,3,2- benzodithiaborole ((CatS 2)BCl) are active for arene borylation, displaying reactivity between that of catecholato- and dichloro-boron electrophiles. [(CatS 2)B(NEt 3)][AlCl 4] is significantly less prone to nucleophile-induced transfer of halide from [AlCl 4] to boron compared to catecholato and dichloro borocations, enabling it to borylate arenes containing nucleophilic -NMe 2 moieties in high conversion (e.g., N,N,4-trimethylaniline and 1,8-bis(dimethylamino) naphthalene). Calculations indicate that the magnitude of positive charge at boron is a key factor in determining the propensity of chloride transfer from [AlCl 4] to boron on addition of a nucleophile. © 2012 American Chemical Society.

Item Type: Article
DOI/Identification number: 10.1021/om201228e
Uncontrolled keywords: Adamantyl groups, Borylation, Chloride transfer, Electrophiles, Halide abstraction, High conversions, Hydride abstraction, Key factors, Lewis Acid, Low-yield, Positive charges, Steric shielding, Abstracting, Benzene, Chlorine compounds, Naphthalene, Nucleophiles, Toluene, Boron
Subjects: Q Science > QD Chemistry
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Giles Tarver
Date Deposited: 29 Jul 2015 15:15 UTC
Last Modified: 29 May 2019 14:56 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/49878 (The current URI for this page, for reference purposes)
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