A Cu-electrocatalytic azidation of -aryl enamines and subsequent denitrogenative annulation for the construction of quinoxaline frameworks is reported. Only 0.5 mol % of copper(II) chloride was employed for this cascade transformation displaying excellent functional-group compatibility even with complex bioactive scaffolds. The efficient electro-oxidative protocol enables the use of NaN as the cheapest azide source. Detailed mechanistic experiments, cyclic voltammetry, and spectroscopic studies provided strong evidence for a dual role of the Cu catalyst in azidyl and iminyl radical generation steps.
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http://dx.doi.org/10.1021/acs.orglett.3c02186 | DOI Listing |
Int J Mol Sci
January 2025
Postovsky Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences, S. Kovalevskoy Street, 22, Ekaterinburg 620137, Russia.
The synthetic approach based on a sequence of Buchwald-Hartwig cross-coupling and annulation through intramolecular oxidative cyclodehydrogenation has been used for the construction of novel 4-alkyl-4-thieno[2',3':4,5]pyrrolo[2,3-]quinoxaline derivatives. For the first time, these polycyclic compounds were evaluated for antimycobacterial activity, including extensively drug-resistant strains. A reasonable bacteriostatic effect against HRv was demonstrated.
View Article and Find Full Text PDFOrg Lett
January 2025
College of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.
Capturing CO is highly valued in the field of organic synthesis, especially underdeveloped dual-CO conversion. In this study, we detail a novel reductive cyclization of 2-indolylanilines with dual CO as a difunctional reagent in the presence of PMHS [poly(methylhydrosiloxane)], delivering methyl-substituted quinoxalines. Furthermore, another chemoselective cyclization with 2-pyrrolylanilines is also realized by converting mono-CO.
View Article and Find Full Text PDFOrg Biomol Chem
January 2025
Jiangsu Key Laboratory of Pesticide Science and Department of Chemistry, College of Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China.
A strategy for trifluoroacetylation of quinoxaline-2(1)-ones has been investigated. This strategy employs masked trifluoroacyl reagents to obtain trifluoroacetylated quinoxaline-2(1)-ones under metal-, catalyst-, and light-free conditions. This approach is distinguished by its functional group compatibility and tolerance, as well as the simplicity of the experimental process, making it suitable for gram-scale synthesis.
View Article and Find Full Text PDFChemistry
January 2025
Shandong Normal University, Chemistry, No.88 Wenhua East Road, 250014, Jinan, CHINA.
Non-fused electron acceptors have obtained increasing curiosity in organic solar cells (OSCs) thanks to simple synthetic route and versatile chemical modification capabilities. However, non-fused acceptors with varying quinoxaline core and as-cast device have rarely been explored, and the molecular structure-photovoltaic performance relationship of such acceptors remains unclear. Herein, two non-fused acceptors L19 and L21 with thienyl substituted non-fluorinated/fluorinated quinoxaline core were developed via five-step synthesis.
View Article and Find Full Text PDFMolecules
December 2024
School of Chemistry and Physics, University of KwaZulu-Natal, Scottsville, Pietermaritzburg 3209, South Africa.
Benzylic C-H oxidation to form carbonyl compounds, such as ketones, is a fundamental transformation in organic synthesis as it allows for the preparation of versatile intermediates. In this review, we highlight the synthesis of aromatic ketones via catalytic, electrochemical, and photochemical oxidation of alkylarenes using different catalysts and oxidants in the past 5 years. Additionally, we also discuss the synthesis of heterocyclic molecules using benzylic C-H oxidation as a key step.
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