Investigating selective hydrogen isotope exchange on unsaturated moieties with active iridium complexes

William Kerr, Richard Mudd, Jack Brown

Research output: Contribution to conferenceSpeech

Abstract

There exist a wide range of reported iridium catalysts which can facilitate hydrogen isotope exchange (HIE) upon aromatic compounds. Within this array, several catalysts stand out for their ability to mediate the HIE under mild conditions, with high levels of isotope incoporation. One key drawback in the labeling protocol with each catalyst is the necessity of an aromatic group to accept the isotopic label, limiting the utility to compounds containing functionalised aromatic skeletons. Our first effort to overcome this limitation was to apply nonaromatic unsaturated compounds, with skeletons related to the aromatic moieties previously labelled. However, each catalyst currently capable of HIE under mild conditions is also capable of olefin hydrogenation, typically under similar reaction conditions. Pleasingly, we found that utilising our developed, commercially available, bulky NHC/phosphine complex (I), under optimised conditions, excellent isotope incorporation is delivered and the alkene reduction is negligible. Furthermore, isotope incorporation is observed exclusively β- to the donor group. We have proposed a mechanism for this mild and novel process, supported by experimental findings, which includes oxidative addition into the β-C-H bond, similar to aromatic HIE.

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Iridium
Isotopes
Hydrogen
Catalysts
phosphine
Alkenes
Unsaturated compounds
Aromatic compounds
Labeling
Hydrogenation
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Keywords

  • hydrogen isotope exchange
  • unsaturated moieties
  • iridium complexes
  • aromatic compounds

Cite this

Kerr, W., Mudd, R., & Brown, J. (2015). Investigating selective hydrogen isotope exchange on unsaturated moieties with active iridium complexes. International Isotope Society, 12th International Symposium on the Synthesis and Application of Isotopically Labelled Compounds, Princeton, United States.
Kerr, William ; Mudd, Richard ; Brown, Jack. / Investigating selective hydrogen isotope exchange on unsaturated moieties with active iridium complexes. International Isotope Society, 12th International Symposium on the Synthesis and Application of Isotopically Labelled Compounds, Princeton, United States.
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abstract = "There exist a wide range of reported iridium catalysts which can facilitate hydrogen isotope exchange (HIE) upon aromatic compounds. Within this array, several catalysts stand out for their ability to mediate the HIE under mild conditions, with high levels of isotope incoporation. One key drawback in the labeling protocol with each catalyst is the necessity of an aromatic group to accept the isotopic label, limiting the utility to compounds containing functionalised aromatic skeletons. Our first effort to overcome this limitation was to apply nonaromatic unsaturated compounds, with skeletons related to the aromatic moieties previously labelled. However, each catalyst currently capable of HIE under mild conditions is also capable of olefin hydrogenation, typically under similar reaction conditions. Pleasingly, we found that utilising our developed, commercially available, bulky NHC/phosphine complex (I), under optimised conditions, excellent isotope incorporation is delivered and the alkene reduction is negligible. Furthermore, isotope incorporation is observed exclusively β- to the donor group. We have proposed a mechanism for this mild and novel process, supported by experimental findings, which includes oxidative addition into the β-C-H bond, similar to aromatic HIE.",
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Kerr, W, Mudd, R & Brown, J 2015, 'Investigating selective hydrogen isotope exchange on unsaturated moieties with active iridium complexes' International Isotope Society, 12th International Symposium on the Synthesis and Application of Isotopically Labelled Compounds, Princeton, United States, 7/06/15 - 11/06/15, .

Investigating selective hydrogen isotope exchange on unsaturated moieties with active iridium complexes. / Kerr, William; Mudd, Richard; Brown, Jack.

2015. International Isotope Society, 12th International Symposium on the Synthesis and Application of Isotopically Labelled Compounds, Princeton, United States.

Research output: Contribution to conferenceSpeech

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T1 - Investigating selective hydrogen isotope exchange on unsaturated moieties with active iridium complexes

AU - Kerr, William

AU - Mudd, Richard

AU - Brown, Jack

PY - 2015/6/11

Y1 - 2015/6/11

N2 - There exist a wide range of reported iridium catalysts which can facilitate hydrogen isotope exchange (HIE) upon aromatic compounds. Within this array, several catalysts stand out for their ability to mediate the HIE under mild conditions, with high levels of isotope incoporation. One key drawback in the labeling protocol with each catalyst is the necessity of an aromatic group to accept the isotopic label, limiting the utility to compounds containing functionalised aromatic skeletons. Our first effort to overcome this limitation was to apply nonaromatic unsaturated compounds, with skeletons related to the aromatic moieties previously labelled. However, each catalyst currently capable of HIE under mild conditions is also capable of olefin hydrogenation, typically under similar reaction conditions. Pleasingly, we found that utilising our developed, commercially available, bulky NHC/phosphine complex (I), under optimised conditions, excellent isotope incorporation is delivered and the alkene reduction is negligible. Furthermore, isotope incorporation is observed exclusively β- to the donor group. We have proposed a mechanism for this mild and novel process, supported by experimental findings, which includes oxidative addition into the β-C-H bond, similar to aromatic HIE.

AB - There exist a wide range of reported iridium catalysts which can facilitate hydrogen isotope exchange (HIE) upon aromatic compounds. Within this array, several catalysts stand out for their ability to mediate the HIE under mild conditions, with high levels of isotope incoporation. One key drawback in the labeling protocol with each catalyst is the necessity of an aromatic group to accept the isotopic label, limiting the utility to compounds containing functionalised aromatic skeletons. Our first effort to overcome this limitation was to apply nonaromatic unsaturated compounds, with skeletons related to the aromatic moieties previously labelled. However, each catalyst currently capable of HIE under mild conditions is also capable of olefin hydrogenation, typically under similar reaction conditions. Pleasingly, we found that utilising our developed, commercially available, bulky NHC/phosphine complex (I), under optimised conditions, excellent isotope incorporation is delivered and the alkene reduction is negligible. Furthermore, isotope incorporation is observed exclusively β- to the donor group. We have proposed a mechanism for this mild and novel process, supported by experimental findings, which includes oxidative addition into the β-C-H bond, similar to aromatic HIE.

KW - hydrogen isotope exchange

KW - unsaturated moieties

KW - iridium complexes

KW - aromatic compounds

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Kerr W, Mudd R, Brown J. Investigating selective hydrogen isotope exchange on unsaturated moieties with active iridium complexes. 2015. International Isotope Society, 12th International Symposium on the Synthesis and Application of Isotopically Labelled Compounds, Princeton, United States.