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Issue 12, 2015
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Iron(iii) bromide catalyzed bromination of 2-tert-butylpyrene and corresponding position-dependent aryl-functionalized pyrene derivatives

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Abstract

The present work probes the bromination mechanism of 2-tert-butylpyrene (1), which regioselectively affords mono-, di-, tri- and tetra-bromopyrenes, by theoretical calculation and detailed experimental methods. The bromine atom may be directed to the K-region (positions 5- and 9-) instead of the more reactive 6- and 8-positions in the presence of iron powder. In this process, FeBr3 plays a significant role to release steric hindrance or lower the activation energy of the rearrangement. The intermediate bromopyrene derivatives were isolated and confirmed by 1H NMR spectrometry, mass spectroscopy and elemental analysis. Further evidence on substitution position originated from a series of aryl substituted pyrene derivatives, which were obtained from the corresponding bromopyrenes on reaction with 4-methoxy-phenylboronic acid by a Suzuki–Miyaura cross-coupling reaction. All position-dependent aryl-functionalized pyrene derivatives are characterized by single X-ray diffraction, 1H/13C NMR, FT-IR and MS, and offered straightforward evidence to support our conclusion. Furthermore, the photophysical properties of a series of compounds were confirmed by fluorescence and absorption, as well as by fluorescence lifetime measurements.

Graphical abstract: Iron(iii) bromide catalyzed bromination of 2-tert-butylpyrene and corresponding position-dependent aryl-functionalized pyrene derivatives

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Publication details

The article was received on 11 Oct 2014, accepted on 03 Dec 2014 and first published on 04 Dec 2014


Article type: Paper
DOI: 10.1039/C4RA12216J
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RSC Adv., 2015,5, 8835-8848

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    Iron(III) bromide catalyzed bromination of 2-tert-butylpyrene and corresponding position-dependent aryl-functionalized pyrene derivatives

    X. Feng, J. Hu, H. Tomiyasu, Z. Tao, C. Redshaw, M. R. J. Elsegood, L. Horsburgh, S. J. Teat, X. Wei and T. Yamato, RSC Adv., 2015, 5, 8835
    DOI: 10.1039/C4RA12216J

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