Sequentially Cu-catalyzed Four- and Five-Component Syntheses of Luminescent 3-Triazolylquinoxalines

3-Triazolylquinoxalines can be readily synthesized by applying two complementary synthetic protocols starting from heterocyclic pi-nucleophiles or (hetero)aryl glyoxylic acids in a consecutive five- or four-component reaction. Conceptually, the sequential use of a single cuprous salt for alkynylatio...

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Bibliographic Details
Published in:Chemistry : a European journal 2019-02
Main Authors: Merkt, Franziska K, Pieper, Konstantin, Klopotowski, Maximilian, Janiak, Christoph, Müller, Thomas J J
Format: Article
Language:English
Online Access:Get full text
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Summary:3-Triazolylquinoxalines can be readily synthesized by applying two complementary synthetic protocols starting from heterocyclic pi-nucleophiles or (hetero)aryl glyoxylic acids in a consecutive five- or four-component reaction. Conceptually, the sequential use of a single cuprous salt for alkynylation and Cu-catalyzed alkyne-azide cycloaddition (CuAAC) in a one-pot fashion sets the stage for activation-alkynylation-cyclo-condensation-CuAAC or glyoxylation-alkynylation-cyclo-condensation-CuAAC sequences in good yields. The diversity-oriented generation of differently substituted 3 triazolylquinoxalines is an excellent entry to tunable emission solvatorchromic fluorophores with triazole ligation. The electronic structure, corroborated by DFT and TD-DFT calculations, rationalizes the charge transfer character of relevant absorptions and large Stokes shifts as well as the electronic innocence of the triazole substituents.
ISSN:1521-3765