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Ru-Catalyzed C-H Arylation of Fluoroarenes with Aryl Halides.


ABSTRACT: Although the ruthenium-catalyzed C-H arylation of arenes bearing directing groups with haloarenes is well-known, this process has never been achieved in the absence of directing groups. We report the first example of such a process and show that unexpectedly the reaction only takes place in the presence of catalytic amounts of a benzoic acid. Furthermore, contrary to other transition metals, the arylation site selectivity is governed by both electronic and steric factors. Stoichiometric and NMR mechanistic studies support a catalytic cycle that involves a well-defined ?(6)-arene-ligand-free Ru(II) catalyst. Indeed, upon initial pivalate-assisted C-H activation, the aryl-Ru(II) intermediate generated is able to react with an aryl bromide coupling partner only in the presence of a benzoate additive. In contrast, directing-group-containing substrates (such as 2-phenylpyridine) do not require a benzoate additive. Deuterium labeling and kinetic isotope effect experiments indicate that C-H activation is both reversible and kinetically significant. Computational studies support a concerted metalation-deprotonation (CMD)-type ruthenation mode and shed light on the unusual arylation regioselectivity.

SUBMITTER: Simonetti M 

PROVIDER: S-EPMC4805314 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature

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Ru-Catalyzed C-H Arylation of Fluoroarenes with Aryl Halides.

Simonetti Marco M   Perry Gregory J P GJ   Cambeiro Xacobe C XC   Juliá-Hernández Francisco F   Arokianathar Jude N JN   Larrosa Igor I  

Journal of the American Chemical Society 20160304 10


Although the ruthenium-catalyzed C-H arylation of arenes bearing directing groups with haloarenes is well-known, this process has never been achieved in the absence of directing groups. We report the first example of such a process and show that unexpectedly the reaction only takes place in the presence of catalytic amounts of a benzoic acid. Furthermore, contrary to other transition metals, the arylation site selectivity is governed by both electronic and steric factors. Stoichiometric and NMR  ...[more]

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