Terminal Alkyne Coupling Reactions through a Ring: Mechanistic Insights and Regiochemical Switching

Caroline M. Storey; Matthew R. Gyton; Rhiann E. Andrew; Adrian B. Chaplin

doi:10.1002/anie.201807028

Terminal Alkyne Coupling Reactions through a Ring: Mechanistic Insights and Regiochemical Switching

Caroline M. Storey, Matthew R. Gyton, Rhiann E. Andrew, Adrian B. Chaplin^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

The mechanism and selectivity of terminal alkyne coupling reactions promoted by rhodium(I) complexes of NHC-based CNC pincer ligands have been investigated. Synthetic and kinetic experiments support E- and gem-enyne formation through a common reaction sequence involving hydrometallation and rate-determining C−C bond reductive elimination. The latter is significantly affected by the ligand topology: Employment of a macrocyclic variant enforced exclusive head-to-head coupling, contrasting the high selectivity for head-to-tail coupling observed for the corresponding acyclic pincer ligand.

Original language	English
Pages (from-to)	12003-12006
Number of pages	4
Journal	Angewandte Chemie - International Edition
Volume	57
Issue number	37
DOIs	https://doi.org/10.1002/anie.201807028
Publication status	Published - 10 Sept 2018

Bibliographical note

Funding Information:
We thank the European Research Council (ERC, grant agreement 637313; C.M.S., M.R.G., A.B.C.), the University of Warwick (R.E.A.), and the Royal Society (UF100592, UF150675; A.B.C.) for financial support. Crystallographic (1, 3, 8) and high-resolution mass-spectrometry data were collected using instruments purchased through support from Advantage West Midlands and the European Regional Development Fund. Crystallographic data for 2, 5, 7, and [Cu(CNC-12)][BAr4F] were collected using an instrument that received funding from the ERC under the European Union≫s Horizon 2020 research and innovation programme (Grant Agreement No. 637313).

Funding Information:
We thank the European Research Council (ERC, grant agreement 637313; C.M.S., M.R.G., A.B.C.), the University of Warwick (R.E.A.), and the Royal Society (UF100592, UF150675; A.B.C.) for financial support. Crystallographic (1, 3, 8) and high-resolution mass-spectrometry data were collected using instruments purchased through support from Advantage West Midlands and the European Regional Development Fund. Crystallographic data for 2, 5, 7, and [Cu(CNC-12)][BArF4] were collected using an instrument that received funding from the ERC under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 637313).

Publisher Copyright:
© 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Keywords

C−C coupling
enynes
macrocyclic ligands
pincer ligands
rhodium

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10.1002/anie.201807028

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title = "Terminal Alkyne Coupling Reactions through a Ring: Mechanistic Insights and Regiochemical Switching",

abstract = "The mechanism and selectivity of terminal alkyne coupling reactions promoted by rhodium(I) complexes of NHC-based CNC pincer ligands have been investigated. Synthetic and kinetic experiments support E- and gem-enyne formation through a common reaction sequence involving hydrometallation and rate-determining C−C bond reductive elimination. The latter is significantly affected by the ligand topology: Employment of a macrocyclic variant enforced exclusive head-to-head coupling, contrasting the high selectivity for head-to-tail coupling observed for the corresponding acyclic pincer ligand.",

keywords = "C−C coupling, enynes, macrocyclic ligands, pincer ligands, rhodium",

author = "Storey, {Caroline M.} and Gyton, {Matthew R.} and Andrew, {Rhiann E.} and Chaplin, {Adrian B.}",

note = "Funding Information: We thank the European Research Council (ERC, grant agreement 637313; C.M.S., M.R.G., A.B.C.), the University of Warwick (R.E.A.), and the Royal Society (UF100592, UF150675; A.B.C.) for financial support. Crystallographic (1, 3, 8) and high-resolution mass-spectrometry data were collected using instruments purchased through support from Advantage West Midlands and the European Regional Development Fund. Crystallographic data for 2, 5, 7, and [Cu(CNC-12)][BAr4F] were collected using an instrument that received funding from the ERC under the European Union≫s Horizon 2020 research and innovation programme (Grant Agreement No. 637313). Funding Information: We thank the European Research Council (ERC, grant agreement 637313; C.M.S., M.R.G., A.B.C.), the University of Warwick (R.E.A.), and the Royal Society (UF100592, UF150675; A.B.C.) for financial support. Crystallographic (1, 3, 8) and high-resolution mass-spectrometry data were collected using instruments purchased through support from Advantage West Midlands and the European Regional Development Fund. Crystallographic data for 2, 5, 7, and [Cu(CNC-12)][BArF4] were collected using an instrument that received funding from the ERC under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 637313). Publisher Copyright: {\textcopyright} 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.",

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AU - Gyton, Matthew R.

AU - Andrew, Rhiann E.

AU - Chaplin, Adrian B.

N1 - Funding Information: We thank the European Research Council (ERC, grant agreement 637313; C.M.S., M.R.G., A.B.C.), the University of Warwick (R.E.A.), and the Royal Society (UF100592, UF150675; A.B.C.) for financial support. Crystallographic (1, 3, 8) and high-resolution mass-spectrometry data were collected using instruments purchased through support from Advantage West Midlands and the European Regional Development Fund. Crystallographic data for 2, 5, 7, and [Cu(CNC-12)][BAr4F] were collected using an instrument that received funding from the ERC under the European Union≫s Horizon 2020 research and innovation programme (Grant Agreement No. 637313). Funding Information: We thank the European Research Council (ERC, grant agreement 637313; C.M.S., M.R.G., A.B.C.), the University of Warwick (R.E.A.), and the Royal Society (UF100592, UF150675; A.B.C.) for financial support. Crystallographic (1, 3, 8) and high-resolution mass-spectrometry data were collected using instruments purchased through support from Advantage West Midlands and the European Regional Development Fund. Crystallographic data for 2, 5, 7, and [Cu(CNC-12)][BArF4] were collected using an instrument that received funding from the ERC under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 637313). Publisher Copyright: © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

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N2 - The mechanism and selectivity of terminal alkyne coupling reactions promoted by rhodium(I) complexes of NHC-based CNC pincer ligands have been investigated. Synthetic and kinetic experiments support E- and gem-enyne formation through a common reaction sequence involving hydrometallation and rate-determining C−C bond reductive elimination. The latter is significantly affected by the ligand topology: Employment of a macrocyclic variant enforced exclusive head-to-head coupling, contrasting the high selectivity for head-to-tail coupling observed for the corresponding acyclic pincer ligand.

AB - The mechanism and selectivity of terminal alkyne coupling reactions promoted by rhodium(I) complexes of NHC-based CNC pincer ligands have been investigated. Synthetic and kinetic experiments support E- and gem-enyne formation through a common reaction sequence involving hydrometallation and rate-determining C−C bond reductive elimination. The latter is significantly affected by the ligand topology: Employment of a macrocyclic variant enforced exclusive head-to-head coupling, contrasting the high selectivity for head-to-tail coupling observed for the corresponding acyclic pincer ligand.

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KW - enynes

KW - macrocyclic ligands

KW - pincer ligands

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JF - Angewandte Chemie - International Edition

IS - 37

ER -

Terminal Alkyne Coupling Reactions through a Ring: Mechanistic Insights and Regiochemical Switching

Abstract

Bibliographical note

Keywords

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