Electrophilic aromatic substitutions of aryltrifluoroborates with retention of the BF3- group: Quantification of the activating and directing effects of the trifluoroborate group

Guillaume Berionni, Varvara Morozova, Maximilian Heininger, Peter Mayer, Paul Knochel, Herbert Mayr

Résultats de recherche: Contribution à un journal/une revueArticle

Résumé

Kinetics and mechanisms of transition-metal free reactions of furyl, thienyl and indolyl trifluoroborates with benzhydrylium (Ar2CH +) and iminium (Me2N+=CHR) ions have been investigated. In contrast to common belief, substitutions at CH positions are often faster than ipso-substitutions of the BF3K group, because BF3K activates the position attached to boron by a factor of 10 3-104 while adjacent CH positions are activated by factors of 105-106. Several reactions that have previously been interpreted as ipso-substitutions actually proceed via initial substitution at a vicinal or remote CH position, followed by protodeborylation. If the proton released during electrophilic substitution at a CH position is trapped by a base, the BF3- group can be preserved. Remote reactions of heteroaryl trifluoroborates with iminium ions provide straightforward access to novel zwitterionic ammonium or iminium trifluoroborates, which have been characterized by single-crystal X-ray analyses.

langue originaleAnglais
Pages (de - à)6317-6324
Nombre de pages8
journalJournal of the American Chemical Society
Volume135
Numéro de publication16
Les DOIs
étatPublié - 24 avr. 2013
Modification externeOui

Empreinte digitale

Substitution reactions
Ions
Boron
Ammonium Compounds
Protons
Metals
X-Rays
Transition metals
Single crystals
X rays
Kinetics

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title = "Electrophilic aromatic substitutions of aryltrifluoroborates with retention of the BF3- group: Quantification of the activating and directing effects of the trifluoroborate group",
abstract = "Kinetics and mechanisms of transition-metal free reactions of furyl, thienyl and indolyl trifluoroborates with benzhydrylium (Ar2CH +) and iminium (Me2N+=CHR) ions have been investigated. In contrast to common belief, substitutions at CH positions are often faster than ipso-substitutions of the BF3K group, because BF3K activates the position attached to boron by a factor of 10 3-104 while adjacent CH positions are activated by factors of 105-106. Several reactions that have previously been interpreted as ipso-substitutions actually proceed via initial substitution at a vicinal or remote CH position, followed by protodeborylation. If the proton released during electrophilic substitution at a CH position is trapped by a base, the BF3- group can be preserved. Remote reactions of heteroaryl trifluoroborates with iminium ions provide straightforward access to novel zwitterionic ammonium or iminium trifluoroborates, which have been characterized by single-crystal X-ray analyses.",
author = "Guillaume Berionni and Varvara Morozova and Maximilian Heininger and Peter Mayer and Paul Knochel and Herbert Mayr",
year = "2013",
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Electrophilic aromatic substitutions of aryltrifluoroborates with retention of the BF3- group : Quantification of the activating and directing effects of the trifluoroborate group. / Berionni, Guillaume; Morozova, Varvara; Heininger, Maximilian; Mayer, Peter; Knochel, Paul; Mayr, Herbert.

Dans: Journal of the American Chemical Society, Vol 135, Numéro 16, 24.04.2013, p. 6317-6324.

Résultats de recherche: Contribution à un journal/une revueArticle

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T1 - Electrophilic aromatic substitutions of aryltrifluoroborates with retention of the BF3- group

T2 - Quantification of the activating and directing effects of the trifluoroborate group

AU - Berionni, Guillaume

AU - Morozova, Varvara

AU - Heininger, Maximilian

AU - Mayer, Peter

AU - Knochel, Paul

AU - Mayr, Herbert

PY - 2013/4/24

Y1 - 2013/4/24

N2 - Kinetics and mechanisms of transition-metal free reactions of furyl, thienyl and indolyl trifluoroborates with benzhydrylium (Ar2CH +) and iminium (Me2N+=CHR) ions have been investigated. In contrast to common belief, substitutions at CH positions are often faster than ipso-substitutions of the BF3K group, because BF3K activates the position attached to boron by a factor of 10 3-104 while adjacent CH positions are activated by factors of 105-106. Several reactions that have previously been interpreted as ipso-substitutions actually proceed via initial substitution at a vicinal or remote CH position, followed by protodeborylation. If the proton released during electrophilic substitution at a CH position is trapped by a base, the BF3- group can be preserved. Remote reactions of heteroaryl trifluoroborates with iminium ions provide straightforward access to novel zwitterionic ammonium or iminium trifluoroborates, which have been characterized by single-crystal X-ray analyses.

AB - Kinetics and mechanisms of transition-metal free reactions of furyl, thienyl and indolyl trifluoroborates with benzhydrylium (Ar2CH +) and iminium (Me2N+=CHR) ions have been investigated. In contrast to common belief, substitutions at CH positions are often faster than ipso-substitutions of the BF3K group, because BF3K activates the position attached to boron by a factor of 10 3-104 while adjacent CH positions are activated by factors of 105-106. Several reactions that have previously been interpreted as ipso-substitutions actually proceed via initial substitution at a vicinal or remote CH position, followed by protodeborylation. If the proton released during electrophilic substitution at a CH position is trapped by a base, the BF3- group can be preserved. Remote reactions of heteroaryl trifluoroborates with iminium ions provide straightforward access to novel zwitterionic ammonium or iminium trifluoroborates, which have been characterized by single-crystal X-ray analyses.

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