Extended sulfonated bipyridine ligands targeting the para-selective borylation of arenes

Iridium-catalysed borylation of arenes is one of the most widely used metal-catalysed C–H activation processes to elaborate aromatic rings. Exercising catalyst control over regioselectivity of the C–H oxidative addition step remains an area of active research. In this paper we describe the synthesis...

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Bibliographic Details
Published inTetrahedron Vol. 117-118; pp. 132831 - 132849
Main Authors Douthwaite, James L., Phipps, Robert J.
Format Journal Article
LanguageEnglish
Published OXFORD Elsevier Ltd 16.07.2022
Elsevier
Subjects
Borylation
Chemistry
Chemistry, Organic
C–H activation
Non-covalent interactions
Para-selectivity
Physical Sciences
Science & Technology
Para-selectivity
C–H activation
Borylation
Non-covalent interactions
ACTIVATION
C-H activation
FUNCTIONAL-GROUP
C-H BORYLATION
CATALYSTS
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Summary:Iridium-catalysed borylation of arenes is one of the most widely used metal-catalysed C–H activation processes to elaborate aromatic rings. Exercising catalyst control over regioselectivity of the C–H oxidative addition step remains an area of active research. In this paper we describe the synthesis of a selection of sulfonated bipyridine ligands in which there is an arene spacer between the sulfonate group and the bipyridine backbone. In comparison to our previous work which achieved meta-selective borylation and in which the sulfonated bipyridine bore no spacer, we hoped that these extended ligands may allow a larger macrocyclic transition state for C–H activation thus favouring the para-position. The synthesised ligands have been evaluated on a series of arenes bearing amides and quaternary ammonium salts at varying distances from the aromatic ring. [Display omitted]
ISSN:0040-4020
1464-5416
DOI:10.1016/j.tet.2022.132831