A two-step multicomponent reaction oxidation protocol is reported herein, which affords novel tunable fluorescent tetracyclic indolizines. The procedure involves a novel 4-center-3-component reaction, which proceeds via a sequential Knoevenagel condensation, [4+1] cycloaddition, and imine condensation to afford imino-indolizines. Products then undergo cyclization and are oxidized to afford fluorescent tetracycles, which are readily tunable through modification of diversity elements.
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http://dx.doi.org/10.1021/acs.joc.1c01280 | DOI Listing |
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November 2024
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.
Olefin-linked covalent organic frameworks (OL-COFs) show great promise for visible-light-driven photocatalysis. Manipulating atomic-level donor-acceptor interactions in OL-COFs is key to understanding their exciton effects in this system. Here, three OL-COFs are presented with orthorhombic lattice structures, synthesized via Knoevenagel polycondensation reaction of terephthalaldehyde and tetratopic monomers featuring phenyl, benzo[c][1,2,5]oxadiazole, and benzo[c][1,2,5]thiadiazole moieties.
View Article and Find Full Text PDFChem Commun (Camb)
August 2024
School of Chemistry, University of Hyderabad, Hyderabad-500046, India.
A one-pot multicomponent approach towards a hybrid heterocyclic pyrano[2,3-]pyrazole-pyrazolone framework involving tandem Knoevenagel condensation, sequential intermolecular 1,6-Michael addition, and 6- cyclization between diynones and pyrazolones, mediated by DBU, has been discovered. This process embodies several green and sustainable chemistry features. Preliminary bioactivity profiling of the new chemical entities indicates neuroprotective and AChE inhibitory activities.
View Article and Find Full Text PDFOrg Biomol Chem
May 2024
Mendeleev University of Chemical Technology, Miusskaya Sq., 9, Moscow 125047, Russian Federation.
A three-component condensation of 2-unsubstituted imidazole -oxides, 3-ketonitriles, and aldehydes is described. The reaction proceeds sequential Knoevenagel condensation/Michael addition under mild, catalyst-free conditions with various substrates. Furthermore, the corresponding 2-functionalized imidazole -oxides can be further dehydrated to ()-2-aroyl-3-(1-imidazol-2-yl)-acrylonitriles, which may also be directly prepared by changing the reaction conditions as a cascade of Knoevenagel condensation/Michael addition/dehydration.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
July 2024
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, Wuhan, 430070, P. R. China.
As an alternative to hydrogen peroxide (HO) production by complex anthraquinone oxidation process, photosynthesis of HO from water and oxygen without sacrificial agents is highly demanded. Herein, a covalently connected molecular heterostructure is synthesized via sequential C-H arylation and Knoevenagel polymerization reactions for visible-light and sacrificial-agent-free HO synthesis. The subsequent copolymerization of the electron-deficient benzodithiophene-4,8-dione (BTD) and the electron-rich biphenyl (B) and p-phenylenediacetonitrile (CN) not only expands the π-conjugated domain but also increases the molecular dipole moment, which largely promotes the separation and transfer of the photoinduced charge carriers.
View Article and Find Full Text PDFJ Org Chem
December 2023
Department of Chemistry, School of Chemical Sciences and Technology, Dr. Harisingh Gour Central University, Sagar 470 003, Madhya Pradesh, India.
A green approach for the synthesis of electrophilic alkenes has been developed via Knoevenagel condensation between active methylene compounds and carbonyl compounds using Mg powder under aqueous conditions. In this strategy, Mg(OH) acts as a catalyst, which was generated in situ by the reaction between metallic Mg (20 mol %) and water. Mg was found to be an efficient, nontoxic, and inexpensive metal catalyst system for producing a range of electrophilic alkenes in excellent yields (≤98%).
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