Synthesis, structure, and optical properties of 3-(1H-1,2,3-triazol-1-yl)-substituted 4H-pyrido[1,2–a]pyrimidin-4-ones and 4H-quinolizin-4-ones

Humar, Tadej (author), Ciber, Luka (author), Grošelj, Uroš (author), Petek, Nejc (author), Štefane, Bogdan (author), Svete, Jurij (author)

Copper-catalyzed cycloadditions of terminal alkynes to 3-azido-4H-pyrido[1,2–a]pyrimidin-4-one and 3-azido-1-cyano-4H-quinolizin-4-one, prepared in four steps from methyl 2-benzoylamino-3-(dimethylamino)propenoate, yielded the corresponding 3-(1H-1,2,3-triazol-1-yl)-substituted 4H-pyrido[1,2–a]pyrimidin-4-ones and 4H-quinolizin-4-ones in 44–90 % isolated yields. The structures of the cycloadducts were determined by $^1$H NMR, $^{13}$C NMR, and 2D NMR techniques (COSY, HSQC, HMBC). The optical properties of the luminescent intermediates and final products were determined. In methanol, the compounds showed absorption at 350–400 nm, emission at 411–526 nm, and quantum yields of ∼5 × 10$^{−2}$. Optical properties depended on the heterocyclic core (pyrido[1,2–a]pyrimidinone or quinolizinone), while the effect of substituents on optical properties was weak.

• Language: English
• Keywords: quinolizines, azaquinolizines, alkynes, copper-catalyzed azide-alkyne cycloadditions, bioconjugation, fluorescent labelling
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 13 str.
• Numbering: Vol. 247, art. 113434
• PID: 20.500.12556/RUL-176451
• UDC: 547.83
• ISSN on article: 0143-7208
• DOI: 10.1016/j.dyepig.2025.113434
• COBISS.SI-ID: 259137283
• Publication date in RUL: 01.12.2025

Record is a part of a journal

• Title: Dyes and pigments
• Shortened title: Dyes pigm.
• Publisher: Elsevier
• ISSN: 0143-7208
• COBISS.SI-ID: 25357056

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: kinolizini, azakinolizini, alkini, z bakrom katalizirane azid-alkin cikloadicije, biokonjugacija, fluorescenčno označevanje