A Ligand-Free Approach towards Coumarin Analogs via Natural Deep Eutectic Solvent-Mediated Suzuki–Miyaura Coupling

A ligand-free approach for the Suzuki-Miyaura cross coupling reaction using Natural Deep Eutectic Solvents (NaDES) towards coumarin analogs is described. A model reaction between the synthetically prepared 3-(4-acetyloxy-phenyl)-6-bromo-4-methyl-coumarin (<b>3b</b>) and phenylboronic aci...

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Main Authors: Annita Katopodi, Nikolaos Nikolaou, Vasiliki Kakokefalou, Eleni Alexandratou, Manolis Matzapetakis, Maria Zervou, Anastasia Detsi
Format: Article
Language:English
Published: MDPI AG 2024-09-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/29/18/4398
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author Annita Katopodi
Nikolaos Nikolaou
Vasiliki Kakokefalou
Eleni Alexandratou
Manolis Matzapetakis
Maria Zervou
Anastasia Detsi
author_facet Annita Katopodi
Nikolaos Nikolaou
Vasiliki Kakokefalou
Eleni Alexandratou
Manolis Matzapetakis
Maria Zervou
Anastasia Detsi
author_sort Annita Katopodi
collection DOAJ
description A ligand-free approach for the Suzuki-Miyaura cross coupling reaction using Natural Deep Eutectic Solvents (NaDES) towards coumarin analogs is described. A model reaction between the synthetically prepared 3-(4-acetyloxy-phenyl)-6-bromo-4-methyl-coumarin (<b>3b</b>) and phenylboronic acid was performed in five different NaDES as well as in pure glycerol, using two inorganic bases and palladium catalysts. The reaction proceeded smoothly in Choline Chloride/Glycerol (ChCl/Gly) and Betaine/Glycerol (Bet/Gly) NaDES at 90 °C in 24 h, affording the desired product in high yields up to 95%. The combination of K<sub>2</sub>CO<sub>3</sub>, Pd(OAc)<sub>2</sub> and ChCl/Gly NaDES provided optimum yields and high purity of the desired compounds, while the solvent was successfully recycled and reused up to two times. The developed methodology is applicable to boronic acids bearing various substituents. The formation of palladium nanoparticles in the reaction mixture was observed, and the size of the nanoparticles was associated with the reaction yield. In addition, in all the glycerol-based NaDES, an effective removal of the acetyl group of the acetyloxy–coumarin analogs was observed; thus, it is noteworthy that the Suzuki–Miyaura coupling and the deacetylation reaction were achieved in one pot. The ten novel coumarin derivatives synthesized were structurally characterized using 1D and 2D NMR spectroscopy and were tested for their cytotoxicity against the A431 squamous cancer cell line, presenting significant activity.
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spelling doaj-art-7e8a6c9cc264436db50bfe195ae355c32025-08-20T01:55:42ZengMDPI AGMolecules1420-30492024-09-012918439810.3390/molecules29184398A Ligand-Free Approach towards Coumarin Analogs via Natural Deep Eutectic Solvent-Mediated Suzuki–Miyaura CouplingAnnita Katopodi0Nikolaos Nikolaou1Vasiliki Kakokefalou2Eleni Alexandratou3Manolis Matzapetakis4Maria Zervou5Anastasia Detsi6Laboratory of Organic Chemistry, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15780 Athens, GreeceLaboratory of Organic Chemistry, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15780 Athens, GreeceLaboratory of Organic Chemistry, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15780 Athens, GreeceLaboratory of Biomedical Optics and Applied Biophysics, School of Electrical and Computer Engineering, National Technical University of Athens, Zografou Campus, 15780 Athens, GreeceInstitute of Chemical Biology, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., 11635 Athens, GreeceInstitute of Chemical Biology, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., 11635 Athens, GreeceLaboratory of Organic Chemistry, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15780 Athens, GreeceA ligand-free approach for the Suzuki-Miyaura cross coupling reaction using Natural Deep Eutectic Solvents (NaDES) towards coumarin analogs is described. A model reaction between the synthetically prepared 3-(4-acetyloxy-phenyl)-6-bromo-4-methyl-coumarin (<b>3b</b>) and phenylboronic acid was performed in five different NaDES as well as in pure glycerol, using two inorganic bases and palladium catalysts. The reaction proceeded smoothly in Choline Chloride/Glycerol (ChCl/Gly) and Betaine/Glycerol (Bet/Gly) NaDES at 90 °C in 24 h, affording the desired product in high yields up to 95%. The combination of K<sub>2</sub>CO<sub>3</sub>, Pd(OAc)<sub>2</sub> and ChCl/Gly NaDES provided optimum yields and high purity of the desired compounds, while the solvent was successfully recycled and reused up to two times. The developed methodology is applicable to boronic acids bearing various substituents. The formation of palladium nanoparticles in the reaction mixture was observed, and the size of the nanoparticles was associated with the reaction yield. In addition, in all the glycerol-based NaDES, an effective removal of the acetyl group of the acetyloxy–coumarin analogs was observed; thus, it is noteworthy that the Suzuki–Miyaura coupling and the deacetylation reaction were achieved in one pot. The ten novel coumarin derivatives synthesized were structurally characterized using 1D and 2D NMR spectroscopy and were tested for their cytotoxicity against the A431 squamous cancer cell line, presenting significant activity.https://www.mdpi.com/1420-3049/29/18/4398Suzuki–Miyaura reactionDeep Eutectic Solventscoumarinspalladium nanoparticles
spellingShingle Annita Katopodi
Nikolaos Nikolaou
Vasiliki Kakokefalou
Eleni Alexandratou
Manolis Matzapetakis
Maria Zervou
Anastasia Detsi
A Ligand-Free Approach towards Coumarin Analogs via Natural Deep Eutectic Solvent-Mediated Suzuki–Miyaura Coupling
Molecules
Suzuki–Miyaura reaction
Deep Eutectic Solvents
coumarins
palladium nanoparticles
title A Ligand-Free Approach towards Coumarin Analogs via Natural Deep Eutectic Solvent-Mediated Suzuki–Miyaura Coupling
title_full A Ligand-Free Approach towards Coumarin Analogs via Natural Deep Eutectic Solvent-Mediated Suzuki–Miyaura Coupling
title_fullStr A Ligand-Free Approach towards Coumarin Analogs via Natural Deep Eutectic Solvent-Mediated Suzuki–Miyaura Coupling
title_full_unstemmed A Ligand-Free Approach towards Coumarin Analogs via Natural Deep Eutectic Solvent-Mediated Suzuki–Miyaura Coupling
title_short A Ligand-Free Approach towards Coumarin Analogs via Natural Deep Eutectic Solvent-Mediated Suzuki–Miyaura Coupling
title_sort ligand free approach towards coumarin analogs via natural deep eutectic solvent mediated suzuki miyaura coupling
topic Suzuki–Miyaura reaction
Deep Eutectic Solvents
coumarins
palladium nanoparticles
url https://www.mdpi.com/1420-3049/29/18/4398
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