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Issue 43, 2014
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Synthesis of fluorescent 2,3,5,6-tetraalkynylpyridines by site-selective Sonogashira-reactions of 2,3,5,6-tetrachloropyridines

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Abstract

4-Substituted 2,3,5,6-tetraalkynylpyridines were prepared by tetra-fold Sonogashira reactions of the corresponding 2,3,5,6-tetrachloropyridines. 2,6-Dialkynyl-3,5-dichloropyridines were prepared by site-selective Sonogashira reactions from various 4-unsubstituted and 4-substituted tetrachloropyridines. Subsequent two-fold Sonogashira reactions of the products allowed for the synthesis of various 2,3,5,6-tetraalkynylpyridines containing different alkynyl groups. The products exhibit interesting UV/Vis and fluorescence properties. The position of absorption and emission bands can be tuned by systematic variation of the type of alkynyl substituent and by the type of substituent located at position 4 of the pyridine moiety. The presence of electron withdrawing substituents or of an alkynyl group at position 4 as well as the presence of donor substituted alkynyl groups at positions 2, 3, 5 and 6 resulted in high fluorescence quantum yields of up to 0.6, presumably due to the push–pull substitution pattern of the molecules.

Graphical abstract: Synthesis of fluorescent 2,3,5,6-tetraalkynylpyridines by site-selective Sonogashira-reactions of 2,3,5,6-tetrachloropyridines

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Publication details

The article was received on 20 Jun 2014, accepted on 11 Aug 2014, published on 13 Aug 2014 and first published online on 13 Aug 2014


Article type: Paper
DOI: 10.1039/C4OB01292E
Citation: Org. Biomol. Chem., 2014,12, 8627-8640
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    Synthesis of fluorescent 2,3,5,6-tetraalkynylpyridines by site-selective Sonogashira-reactions of 2,3,5,6-tetrachloropyridines

    P. Ehlers, A. Petrosyan, A. Neubauer, T. Bröse, S. Lochbrunner, T. V. Ghochikyan, A. S. Saghyan and P. Langer, Org. Biomol. Chem., 2014, 12, 8627
    DOI: 10.1039/C4OB01292E

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