Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Sep 16;15(39):16210-16215.
doi: 10.1039/d4sc03781b. Online ahead of print.

Metal-free alkyne annulation enabling π-extension of boron-doped polycyclic aromatic hydrocarbons

Mandala Anitha  1 , To-Jen Chin  1 , Guan-Cheng Liu  1 , Chi-Tien Hsieh  2 , Kuan-Hua Wang  2 , Shu-Li Li  1 , Mu-Jeng Cheng  2 , Jeffrey M Farrell  1   3
Affiliations

Metal-free alkyne annulation enabling π-extension of boron-doped polycyclic aromatic hydrocarbons

Mandala Anitha et al. Chem Sci. .

Abstract

A C-H functionalizing annulation reaction of boron-doped polycyclic aromatic hydrocarbons (PAHs) with alkynes is described. This metal-free π-extension provides a new synthetic route to fusion atom B-doped polycyclic aromatic hydrocarbons (PAHs) that is demonstrated with the synthesis of a family of new, functionalized, structurally constrained 6a,15a-diborabenzo[tuv]naphtho[2,1-b]picenes. These annulation products exhibit deep LUMO energy levels, strong visible-range absorptions, and sterically accessible π-systems that can adopt herringbone or π-stacked solid-state structures based on choice of substituents. From regioselectivity and DFT calculations, we propose an annulation mechanism involving intramolecular electrophilic aromatic substitution of a zwitterionic intermediate.

PubMed Disclaimer

Conflict of interest statement

There are no conflicts to declare.

Figures

Fig. 1
Fig. 1. Examples of structurally constrained polybenzenoid fusion atom B-doped PAHs.9a,9d–f
Fig. 2
Fig. 2. A schematic example of annulative π-extension (left) compared to the alkyne annulation of B-doped PAHs described herein (right).
Scheme 1
Scheme 1. Formation of 3a by bromination of 1 followed by alkyne annulation. Compound 3a is illustrated by its solid-state structure. C: black, B: yellow-green, H atoms omitted for clarity.
Fig. 3
Fig. 3. DFT-calculated enthalpy and Gibbs free energy profile of the formation of 3a. The structures were optimized in CPCM solvation model in CH2Cl2.
Scheme 2
Scheme 2. Annulative syntheses of extended fusion atom B-doped PAHs.
Fig. 4
Fig. 4. (a) Solid-state structure of 5a determined by X-ray crystallography. C: black, B: yellow-green, H atoms omitted for clarity. (b) Frontier molecular orbitals of 5a from DFT calculations (isosurfaces = 0.07 Å−3). (c) NICS(1) values calculated for rings of 5a (B3LYP-D3(BJ)/def2-TZVP//B3LYP-D3(BJ)/def2-SVP).
Fig. 5
Fig. 5. (a) Side-on views of solid-state packing structures of 5d, 5c, 5f, 5a, and 5g. (b) Alternate view of the π-stacked structure of 5g. (c) Diagram illustrating close contacts of thienyl groups of 5g and highlighting a representative trimeric sub-stack (red) of 5g molecules with two different 3-thienyl orientations (labelled with diamonds or squares). C: black, B: yellow-green, F: green S: yellow, H: grey, selected H atoms omitted for clarity.
Fig. 6
Fig. 6. (a) UV-Vis spectra of 3a and 5a–j (10−6–10−5 M in o-C6H4Cl2, 298 K). (b) Cyclic voltammogram of 5e (9.0 × 10−4 M in 0.1 M n-Bu4NPF6o-C6H4Cl2, 298 K).
See this image and copyright information in PMC

References

    1. Narita A. Wang X.-Y. Feng X. Müllen K. Chem. Soc. Rev. 2015;44:6616. doi: 10.1039/C5CS00183H. - DOI - PubMed
    1. Stępień M. Gońka E. Żyła M. Sprutta N. Chem. Rev. 2017;117:3479. doi: 10.1021/acs.chemrev.6b00076. - DOI - PubMed
    2. Wang X.-Y. Yao X. Narita A. Müllen K. Acc. Chem. Res. 2019;52:2491. doi: 10.1021/acs.accounts.9b00322. - DOI - PMC - PubMed
    3. Borissov A. Maurya Y. K. Moshniaha L. Wong W.-S. Żyła-Karwowska M. Stępień M. Chem. Rev. 2022;122:565. doi: 10.1021/acs.chemrev.1c00449. - DOI - PMC - PubMed
    1. Yamaguchi S. Wakamiya A. Pure Appl. Chem. 2006;78:1413. doi: 10.1351/pac200678071413. - DOI
    2. von Grotthuss E. John A. Kaese T. Wagner M. Asian J. Org. Chem. 2018;7:37. doi: 10.1002/ajoc.201700495. - DOI
    3. Mellerup S. K. Wang S. Trends Chem. 2019;1:77. doi: 10.1016/j.trechm.2019.01.003. - DOI
    1. Matsuo K. Saito S. Yamaguchi S. Angew. Chem., Int. Ed. 2016;55:11984. doi: 10.1002/anie.201605221. - DOI - PubMed
    2. Kushida T. Shirai S. Ando N. Okamoto T. Ishii H. Matsui H. Yamagishi M. Uemura T. Tsurumi J. Watanabe S. Takeya J. Yamaguchi S. J. Am. Chem. Soc. 2017;139:14336. doi: 10.1021/jacs.7b05471. - DOI - PubMed
    1. Farrell J. M. Mützel C. Bialas D. Rudolf M. Menekse K. Krause A.-M. Stolte M. Würthner F. J. Am. Chem. Soc. 2019;141:9096. doi: 10.1021/jacs.9b04675. - DOI - PubMed

LinkOut - more resources