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Sequential Cu‐Catalyzed Four‐ and Five‐Component Syntheses of Luminescent 3‐Triazolylquinoxalines
Author(s) -
Merkt Franziska K.,
Pieper Konstantin,
Klopotowski Maximilian,
Janiak Christoph,
Müller Thomas J. J.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201900277
Subject(s) - nucleophile , chemistry , cycloaddition , combinatorial chemistry , alkynylation , alkyne , catalysis , azide , salt (chemistry) , aryl , triazole , organic chemistry , alkyl
3‐Triazolylquinoxalines can be readily synthesized by applying two complementary synthetic protocols starting from heterocyclic π nucleophiles or (hetero)aryl glyoxylic acids in a consecutive four‐ or five‐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‐cyclocondensation‐CuAAC or glyoxylation‐alkynylation‐cyclocondensation‐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.