The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration: Mechanistic and functionalisation studies

K. Yuan; R. J. Kahan; C. Si; A. Williams; S. Kirschner; M. Uzelac; E. Zysman-Colman; M. J. Ingleson

doi:10.1039/c9sc05404a

The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration: Mechanistic and functionalisation studies

K. Yuan, R. J. Kahan, C. Si, A. Williams, S. Kirschner, M. Uzelac, E. Zysman-Colman, M. J. Ingleson

Department of Chemistry

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

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Abstract

The synthesis of a range of brominated-B_n-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr₃ with appropriately substituted alkynes via a bromoboration/electrophilic C-H borylation sequence. The brominated-B_n-PAHs were isolated as either the borinic acids or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B₂-doped PAHs (with one example having a reduction potential of E_1/2 = -0.96 V versus Fc⁺/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-Bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters directly from internal alkynes. Bromoboration/C-H borylation installs useful C-Br units onto the B_n-PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B₂-PAH. The resultant D-A-D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.

Original language	English
Pages (from-to)	3258-3267
Number of pages	10
Journal	Chemical Science
Volume	11
Issue number	12
DOIs	https://doi.org/10.1039/c9sc05404a
Publication status	Published - 28 Mar 2020

Bibliographical note

Funding Information:
The research leading to these results has received funding from the European Research Council under the Horizon 2020 Research and Innovation Program (Grant no. 769599), the Leverhulme Trust (RPG-2014-340) and the EPSRC (EP/P010482/ 1). C. Si thanks the China Scholarship Council (201806890001). Dr G. Nichol is thanked for the collection of X-ray diffraction data, Dr G. Whitehead for the structure of 2a and Dr A. Woodward for collecting photophysical data on compound 2c (see ESI‡).

Publisher Copyright:
This journal is © The Royal Society of Chemistry.

Funding

The research leading to these results has received funding from the European Research Council under the Horizon 2020 Research and Innovation Program (Grant no. 769599), the Leverhulme Trust (RPG-2014-340) and the EPSRC (EP/P010482/ 1). C. Si thanks the China Scholarship Council (201806890001). Dr G. Nichol is thanked for the collection of X-ray diffraction data, Dr G. Whitehead for the structure of 2a and Dr A. Woodward for collecting photophysical data on compound 2c (see ESI‡).

ASJC Scopus subject areas

General Chemistry

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title = "The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration: Mechanistic and functionalisation studies",

abstract = "The synthesis of a range of brominated-Bn-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr3 with appropriately substituted alkynes via a bromoboration/electrophilic C-H borylation sequence. The brominated-Bn-PAHs were isolated as either the borinic acids or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B2-doped PAHs (with one example having a reduction potential of E1/2 = -0.96 V versus Fc+/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-Bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters directly from internal alkynes. Bromoboration/C-H borylation installs useful C-Br units onto the Bn-PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B2-PAH. The resultant D-A-D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.",

author = "K. Yuan and Kahan, {R. J.} and C. Si and A. Williams and S. Kirschner and M. Uzelac and E. Zysman-Colman and Ingleson, {M. J.}",

note = "Funding Information: The research leading to these results has received funding from the European Research Council under the Horizon 2020 Research and Innovation Program (Grant no. 769599), the Leverhulme Trust (RPG-2014-340) and the EPSRC (EP/P010482/ 1). C. Si thanks the China Scholarship Council (201806890001). Dr G. Nichol is thanked for the collection of X-ray diffraction data, Dr G. Whitehead for the structure of 2a and Dr A. Woodward for collecting photophysical data on compound 2c (see ESI‡). Publisher Copyright: This journal is {\textcopyright} The Royal Society of Chemistry.",

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AU - Yuan, K.

AU - Kahan, R. J.

AU - Si, C.

AU - Williams, A.

AU - Kirschner, S.

AU - Uzelac, M.

AU - Zysman-Colman, E.

AU - Ingleson, M. J.

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PY - 2020/3/28

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N2 - The synthesis of a range of brominated-Bn-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr3 with appropriately substituted alkynes via a bromoboration/electrophilic C-H borylation sequence. The brominated-Bn-PAHs were isolated as either the borinic acids or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B2-doped PAHs (with one example having a reduction potential of E1/2 = -0.96 V versus Fc+/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-Bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters directly from internal alkynes. Bromoboration/C-H borylation installs useful C-Br units onto the Bn-PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B2-PAH. The resultant D-A-D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.

AB - The synthesis of a range of brominated-Bn-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr3 with appropriately substituted alkynes via a bromoboration/electrophilic C-H borylation sequence. The brominated-Bn-PAHs were isolated as either the borinic acids or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B2-doped PAHs (with one example having a reduction potential of E1/2 = -0.96 V versus Fc+/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-Bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters directly from internal alkynes. Bromoboration/C-H borylation installs useful C-Br units onto the Bn-PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B2-PAH. The resultant D-A-D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.

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ER -

The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration: Mechanistic and functionalisation studies

Abstract

Bibliographical note

Funding

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