Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex

Miles Wilklow-Marnell, Bo Li, Tian Zhou, Karsten Krogh-Jespersen, William W. Brennessel, Thomas J. Emge, Alan S Goldman, William D. Jones

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The pincer-iridium fragment (iPrPCP)Ir (RPCP = ?3-2,6-C6H3(CH2PR2)2) has been found to catalyze the dehydrogenative coupling of vinyl arenes to afford predominantly (E,E)-1,4-diaryl-1,3-butadienes. The eliminated hydrogen can undergo addition to another molecule of vinyl arene, resulting in an overall disproportionation reaction with 1 equiv of ethyl arene formed for each equivalent of diarylbutadiene produced. Alternatively, sacrificial hydrogen acceptors (e.g., tert-butylethylene) can be added to the solution for this purpose. Diarylbutadienes are isolated in moderate to good yields, up to ca. 90% based on the disproportionation reaction. The results of DFT calculations and experiments with substituted styrenes indicate that the coupling proceeds via double C-H addition of a styrene molecule, at β-vinyl and ortho-aryl positions, to give an iridium(III) metalloindene intermediate; this intermediate then adds a β-vinyl C-H bond of a second styrene molecule before reductively eliminating product. Several metalloindene complexes have been isolated and crystallographically characterized. In accord with the proposed mechanism, substitution at the ortho-aryl positions of the styrene precludes dehydrogenative homocoupling. In the case of 2,4,6-trimethylstyrene, dehydrogenative coupling of β-vinyl and ortho-methyl C-H bonds affords dimethylindene, demonstrating that the dehydrogenative coupling is not limited to C(sp2)-H bonds.

Original languageEnglish
Pages (from-to)8977-8989
Number of pages13
JournalJournal of the American Chemical Society
Volume139
Issue number26
DOIs
Publication statusPublished - Jul 5 2017

Fingerprint

Iridium
Styrene
Molecules
Hydrogen
Styrenes
Discrete Fourier transforms
Substitution reactions
Butadiene
Experiments

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Wilklow-Marnell, M., Li, B., Zhou, T., Krogh-Jespersen, K., Brennessel, W. W., Emge, T. J., ... Jones, W. D. (2017). Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex. Journal of the American Chemical Society, 139(26), 8977-8989. https://doi.org/10.1021/jacs.7b03433

Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex. / Wilklow-Marnell, Miles; Li, Bo; Zhou, Tian; Krogh-Jespersen, Karsten; Brennessel, William W.; Emge, Thomas J.; Goldman, Alan S; Jones, William D.

In: Journal of the American Chemical Society, Vol. 139, No. 26, 05.07.2017, p. 8977-8989.

Research output: Contribution to journalArticle

Wilklow-Marnell, M, Li, B, Zhou, T, Krogh-Jespersen, K, Brennessel, WW, Emge, TJ, Goldman, AS & Jones, WD 2017, 'Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex', Journal of the American Chemical Society, vol. 139, no. 26, pp. 8977-8989. https://doi.org/10.1021/jacs.7b03433
Wilklow-Marnell M, Li B, Zhou T, Krogh-Jespersen K, Brennessel WW, Emge TJ et al. Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex. Journal of the American Chemical Society. 2017 Jul 5;139(26):8977-8989. https://doi.org/10.1021/jacs.7b03433
Wilklow-Marnell, Miles ; Li, Bo ; Zhou, Tian ; Krogh-Jespersen, Karsten ; Brennessel, William W. ; Emge, Thomas J. ; Goldman, Alan S ; Jones, William D. / Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex. In: Journal of the American Chemical Society. 2017 ; Vol. 139, No. 26. pp. 8977-8989.
@article{df57809edf1140b299a9ad5b65274217,
title = "Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex",
abstract = "The pincer-iridium fragment (iPrPCP)Ir (RPCP = ?3-2,6-C6H3(CH2PR2)2) has been found to catalyze the dehydrogenative coupling of vinyl arenes to afford predominantly (E,E)-1,4-diaryl-1,3-butadienes. The eliminated hydrogen can undergo addition to another molecule of vinyl arene, resulting in an overall disproportionation reaction with 1 equiv of ethyl arene formed for each equivalent of diarylbutadiene produced. Alternatively, sacrificial hydrogen acceptors (e.g., tert-butylethylene) can be added to the solution for this purpose. Diarylbutadienes are isolated in moderate to good yields, up to ca. 90{\%} based on the disproportionation reaction. The results of DFT calculations and experiments with substituted styrenes indicate that the coupling proceeds via double C-H addition of a styrene molecule, at β-vinyl and ortho-aryl positions, to give an iridium(III) metalloindene intermediate; this intermediate then adds a β-vinyl C-H bond of a second styrene molecule before reductively eliminating product. Several metalloindene complexes have been isolated and crystallographically characterized. In accord with the proposed mechanism, substitution at the ortho-aryl positions of the styrene precludes dehydrogenative homocoupling. In the case of 2,4,6-trimethylstyrene, dehydrogenative coupling of β-vinyl and ortho-methyl C-H bonds affords dimethylindene, demonstrating that the dehydrogenative coupling is not limited to C(sp2)-H bonds.",
author = "Miles Wilklow-Marnell and Bo Li and Tian Zhou and Karsten Krogh-Jespersen and Brennessel, {William W.} and Emge, {Thomas J.} and Goldman, {Alan S} and Jones, {William D.}",
year = "2017",
month = "7",
day = "5",
doi = "10.1021/jacs.7b03433",
language = "English",
volume = "139",
pages = "8977--8989",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "26",

}

TY - JOUR

T1 - Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex

AU - Wilklow-Marnell, Miles

AU - Li, Bo

AU - Zhou, Tian

AU - Krogh-Jespersen, Karsten

AU - Brennessel, William W.

AU - Emge, Thomas J.

AU - Goldman, Alan S

AU - Jones, William D.

PY - 2017/7/5

Y1 - 2017/7/5

N2 - The pincer-iridium fragment (iPrPCP)Ir (RPCP = ?3-2,6-C6H3(CH2PR2)2) has been found to catalyze the dehydrogenative coupling of vinyl arenes to afford predominantly (E,E)-1,4-diaryl-1,3-butadienes. The eliminated hydrogen can undergo addition to another molecule of vinyl arene, resulting in an overall disproportionation reaction with 1 equiv of ethyl arene formed for each equivalent of diarylbutadiene produced. Alternatively, sacrificial hydrogen acceptors (e.g., tert-butylethylene) can be added to the solution for this purpose. Diarylbutadienes are isolated in moderate to good yields, up to ca. 90% based on the disproportionation reaction. The results of DFT calculations and experiments with substituted styrenes indicate that the coupling proceeds via double C-H addition of a styrene molecule, at β-vinyl and ortho-aryl positions, to give an iridium(III) metalloindene intermediate; this intermediate then adds a β-vinyl C-H bond of a second styrene molecule before reductively eliminating product. Several metalloindene complexes have been isolated and crystallographically characterized. In accord with the proposed mechanism, substitution at the ortho-aryl positions of the styrene precludes dehydrogenative homocoupling. In the case of 2,4,6-trimethylstyrene, dehydrogenative coupling of β-vinyl and ortho-methyl C-H bonds affords dimethylindene, demonstrating that the dehydrogenative coupling is not limited to C(sp2)-H bonds.

AB - The pincer-iridium fragment (iPrPCP)Ir (RPCP = ?3-2,6-C6H3(CH2PR2)2) has been found to catalyze the dehydrogenative coupling of vinyl arenes to afford predominantly (E,E)-1,4-diaryl-1,3-butadienes. The eliminated hydrogen can undergo addition to another molecule of vinyl arene, resulting in an overall disproportionation reaction with 1 equiv of ethyl arene formed for each equivalent of diarylbutadiene produced. Alternatively, sacrificial hydrogen acceptors (e.g., tert-butylethylene) can be added to the solution for this purpose. Diarylbutadienes are isolated in moderate to good yields, up to ca. 90% based on the disproportionation reaction. The results of DFT calculations and experiments with substituted styrenes indicate that the coupling proceeds via double C-H addition of a styrene molecule, at β-vinyl and ortho-aryl positions, to give an iridium(III) metalloindene intermediate; this intermediate then adds a β-vinyl C-H bond of a second styrene molecule before reductively eliminating product. Several metalloindene complexes have been isolated and crystallographically characterized. In accord with the proposed mechanism, substitution at the ortho-aryl positions of the styrene precludes dehydrogenative homocoupling. In the case of 2,4,6-trimethylstyrene, dehydrogenative coupling of β-vinyl and ortho-methyl C-H bonds affords dimethylindene, demonstrating that the dehydrogenative coupling is not limited to C(sp2)-H bonds.

UR - http://www.scopus.com/inward/record.url?scp=85021929133&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85021929133&partnerID=8YFLogxK

U2 - 10.1021/jacs.7b03433

DO - 10.1021/jacs.7b03433

M3 - Article

VL - 139

SP - 8977

EP - 8989

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 26

ER -